Lycoming YO-233-B2A Maintenance Manual Download

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Engine Maintenance Manual

YO-233-B2A Engine

February 2021

Part No. MM-YO-233-B2A
(Supersedes Maintenance Manual LM-YO-233, dated June 2012)

Summary of Contents for YO-233-B2A

Page 2: ... 7222 Email Technicalsupport lycoming com Lycoming s regular business hours are Monday through Friday from 8 00AM through 5 00PM Eastern Time 5 GMT Visit us Online www lycoming com NOTE Lycoming recommends that owners of this manual sign up for email notification on the Technical Publications page of our website https www lycoming com contact knowledge base publications By submitting your email ad...

Page 3: ...intenance Manual MM YO 233 B2A Supersedes Maintenance Manual LM YO 233 dated June 2012 MM YO 233 B2A has been formatted and incorporates changes included in recently released and FAA approved maintenance manuals This manual contains the same basic information as LM YO 233 with significant changes to several chapters including 05 00 05 30 05 50 12 10 72 30 and 74 30 This manual also includes a desc...

Page 4: ...TEO 540 A1A Engine Maintenance Manual Record of Revisions 2021 Avco Corporation All Rights Reserved Page ii February 2021 YO 233 B2A Engine Maintenance Manual This page intentionally left blank ...

Page 5: ...in the Search box on the website Number Incorporation Date Subject S B 369 02 21 Engine Inspection after Overspeed S B 388 02 21 Procedure to Determine Exhaust Valve and Guide Condition S B 398 02 21 Recommended Corrective Action for Use of Incorrect Fuel S B 399 02 21 Action to Take If Loss of Oil Pressure S B 401 02 21 Recommendations for Aircraft Struck by Lightning S B 480 02 21 I Oil Filter C...

Page 6: ...233 B2A Engine Maintenance Manual SERVICE DOCUMENT LIST CONT Number Incorporation Date Subject S L L162 02 21 Heli Coil Service Repair Kit S L L171 02 21 General Aspects of Spectrometric Oil Analysis S L L192 02 21 Spark Plug Fouling S L L197 02 21 Recommendations to Avoid Valve Sticking S L L283 02 21 Alternate Ignition System ...

Page 7: ...ractices 2 General Engine Inspection Criteria 4 Requirements for Engine Maintenance 4 Approved Parts 4 Corrosion Prevention 5 Painting the Engine and Engine Components 5 Limits and Clearances 7 Inspections 7 Time Limits Inspections 05 10 General 9 Engine Inspection Schedule for YO 233 B2A Engines 9 Time Limits Maintenance Checks Scheduled Maintenance Checks 05 20 Visual Inspection 11 10 Hour Initi...

Page 8: ... 40 Cleaning Methods for Non Destructive Testing 41 Time Limits Maintenance Checks Unscheduled Maintenance 05 50 Lightning Strike After a lightning strike 43 Engine Overspeed 43 Table 1 Overspeed Values for YO 233 B2A Engines 44 Incorrect Fuel or Fuel Contamination 45 Soaked Engine 46 Engine on Fire or Near a Fire 47 Hydraulic Lock 47 Volcanic Ash Particulate Contamination 47 Table 2 Action to Tak...

Page 9: ...nspection of the Oil Filter Element and Oil Suction Screen 66 Table 3 Guidelines for Identification of Metal Particulates and Chips Corrective Action 67 Table 4 Guidelines for Particle Quantity and Size on Oil Filter or Oil Suction Screen 69 Recommended Corrective Action Options 71 Table 5 Recommended Corrective Action Options 71 Fault Isolation 12 30 General 73 Fault Isolation Guide 73 Table 1 Fa...

Page 10: ...n 101 Cylinder Borescope Inspection 102 Table 3 Borescope Inspection Steps Results and Corrective Action 103 Exhaust Valve and Guide Inspection 103 Cylinder Removal 109 Piston Removal 112 Connecting Rod Removal 113 Cylinder Assembly Inspection 114 Piston Inspection 119 Connecting Rod Inspection 123 Connecting Rod Bushing Replacement 126 Connecting Rod Parallelism Squareness Check 128 Connecting Ro...

Page 11: ...4 Starter Ring Gear Support Replacement Procedure 154 Induction System 72 80 System Description 155 Induction System Inspection Procedure 155 Engine Fuel and Control General 73 00 System Description 157 Engine Fuel and Control Distribution 73 10 Fuel System Inspection Procedure 159 Fuel Filter Inspection Procedure 159 Ignition System Maintenance 74 00 Ignition System Description 161 Ignition Syste...

Page 12: ...66 Table 2 Spark Plug Rotation Scheme 166 Spark Plug Installation 166 Electronic Ignition System 74 30 Champion EIS Ignition System 169 Remove the EIS 169 Install the EIS 169 Light Speed Plasma III and Magneto Ignition System 169 Convert the Engine from the Champion EIS Ignition System to the Light Speed Plasma III and Magneto Ignition System 169 Magneto Inspection 170 Magneto to Engine Timing Che...

Page 13: ...R Federal Aviation and Space Regulation FOD Foreign Object Debris ft lb Foot Pound torque H hr Hour I ID Inside Diameter in lb Inch Pound torque in Inch inches IOM YO 233 B2A Engine Installation and Operation Manual M Max Maximum MEK Methyl Ethyl Ketone O OEM Original Equipment Manufacturer OHM Direct Drive Overhaul Manual P psi Pounds per square inch Q Qt Quart R rpm Revolutions per Minute S SAE ...

Page 14: ...ations and Acronyms 2021 Avco Corporation All Rights Reserved Page xii February 2021 YO 233 B2A Engine Maintenance Manual SMOH Since Major Overhaul STC Supplemental Type Certificate T TBO Time Between Overhaul TDC Top Dead Center V V Volt Voltage ...

Page 15: ...33 B2A Series Engine Figure 1 is an ASTM F2339 compliant direct drive four cylinder carbureted horizontally opposed wet sump air cooled engine Refer to Figure 1 Figure 1 YO 233 B2A Series Engine Engine Model Nomenclature This table shows the definition of each letter and number in the basic engine model number Model Number Meaning Y Non Certified O Horizontally Opposed 233 Displacement in cubic in...

Page 16: ...ged refer to the latest revision of Service Instruction No SI 1304 for data plate replacement information Figure 2 Engine Data Plate Cylinder Number Designations The propeller is at the front of the engine and the accessories are at the rear of the engine In a top view of the engine the left side cylinders are 2 4 Cylinder 2 is at the front of the engine Refer to Figure 3 In a top view of the engi...

Page 17: ...S LYCOMING ENGINES SERVICE DOCUMENTS WRITTEN AT A LATER DATE OVERRIDE PROCEDURES IN THIS MANUAL UNLESS OTHERWISE SPECIFIED PROCEDURES IN THIS MANUAL MUST BE DONE BY QUALIFIED PERSONNEL WITH THE REQUISITE CERTIFICATIONS Before you do maintenance on the YO 233 B2A engine read this manual in its entirety Obey all procedures and inspections in this manual NOTICE If you do not obey the maintenance proc...

Page 18: ...actices not related to personal injury NOTICE In this manual the word recommend refers to best practices Service Bulletins Service Instructions and Service Letters As advancements in technological applications on this engine continue Lycoming will make future revisions to this manual However if more timely distribution is necessary Lycoming supplies up to date Service Bulletins SBs Service Instruc...

Page 19: ...ed to display detailed information in an organized format Tables always start as Table 1 in each chapter Checklists are used to display a list of tasks to be completed as part of a specific procedure Checklists are not numbered because they are used as a reference tool contained within the procedure Copyright This publication is a copyrighted work All rights reserved by Lycoming Engines Content in...

Page 20: ...TEO 540 A1A Engine Maintenance Manual Introduction 2021 Avco Corporation All Rights Reserved Page xviii February 2021 YO 233 B2A Engine Maintenance Manual This page intentionally left blank ...

Page 21: ... test operational test and fuels to be used are included in the YO 233 B2A Engine Installation and Operation Manual 2 List of Tools for Maintenance A Table 1 identifies tools used for maintenance Table 1 Tools for Maintenance Tool Purpose Champion Tool CT 470 Cut open oil filter Borescope Cylinder Borescope Inspection Aviation Mechanic s Tools ST 25 Compressor Valve Spring ST 131 Tension Gage Meas...

Page 22: ...sis for 30 days or more or it has been flown or stored in humid dusty or volcanic ash conditions overhaul or rebuild could be necessary before the 2200 hours or 12 year TBO 5 Safety Precautions Before Engine Maintenance WARNING BEFORE THE START OF ANY SERVICE OR MAINTENANCE ON AN INSTALLED ENGINE OR AN ENGINE ON A TEST STAND CONNECTED TO POWER ENSURE THE IGNITION SWITCH IS TURNED OFF AND DISABLE D...

Page 23: ... the stud or bolt and the other end flat against the nut 6 Torque a castellated or slotted nut to the value specified in this manual or the latest revision of the Service Table of Limits SSP 1776 if necessary turn the nut up to one additional hex to align the slot in the nut with the hole in the bolt 7 If a lockplate is required when installing a bolt torque the nut to the value specified in this ...

Page 24: ...ing visual inspection replace engine components including the crankcase oil sump and accessory housing with Replace the crankcase oil sump or accessory housing if there is any raised metal on surfaces Replace the crankcase oil sump or accessory housing if there is any scratch ding dent or pit that exceeds 0 050 in 1 27 mm depth Replace the crankcase if the dowels do not fully seat into the crankca...

Page 25: ...onent Do not get paint on any mating surfaces or under the cylinder hold down nuts There must be metal to metal contact to ensure correct torque Mask mating surfaces and the area where the nut will contact the component surface Table 2 includes paint stripping and painting guidelines for components All paint is to be sprayed however if it is necessary to use a brush use care to prevent an accumula...

Page 26: ...type enamel AMS3125C or equivalent MIL E 7729 properly thinned with Toluene or equivalent AMS3180 or equivalent Federal Spec TT T 548 1 Remove all old paint from the cylinder Paint strippers are usually organic solvents like MEK or acetone or toluene etc and typically will not cause any damage to metals A vapor degreaser is best suited for this purpose NOTICE Masking tape corks plugs metal covers ...

Page 27: ...d Clearances Refer to the latest revision of Service Table of Limits SSP 1776 for the following Backlash and end clearance of gears Clearance between mating machined parts Clearance between moving parts that touch Torque limits for various nuts screws and fasteners 13 Inspections NOTICE Inspections in this section refer to reusable items that do not require replacement in accordance with the lates...

Page 28: ...e the bearing surfaces of all gears for deep scratches 4 Remove minor abrasions with a fine abrasive cloth C Screwed Fitting Inspection 1 Examine the condition of the threads on screwed fittings threaded fastenings or plugs 2 Remove small nicks and burrs with a small file fine abrasive cloth or stone 3 If the part cannot be repaired by polishing it discard it and replace it with a new one 4 If the...

Page 29: ...ce whichever occurs first If one or more new engine cylinders and or piston rings have been installed If the rate of oil consumption has not stabilized repeat this inspection after the next 25 hours of operation 25 hour Initial and Routine Engine Inspection in Chapter 05 20 25 hours after 25 hour Initial Operation Inspection After every 50 hours of operation or every 4 months whichever occurs firs...

Page 31: ... THE PROPELLER TO TURN WHICH CAN LEAD TO DEATH OR SERIOUS INJURY OR A PROPELLER STRIKE B Required tools Basic aviation mechanic s tools Flashlight Mirror C Complete the visual inspection as follows 1 Set all ignition and electrical switches to the OFF position 2 Remove the engine cowling from the aircraft for access to the engine and its compartment CAUTION IF VOLCANIC ASH IS SUSPECTED ON THE ENGI...

Page 32: ...r defective parts THE WIRING HARNESS MUST BE INTACT FOR CORRECT ENGINE OPERATION 9 Make sure that the wiring harness and its connectors are attached correctly and not damaged 10 Examine the wiring harness for correct attachment to the electrical connectors and engine broken or frayed wire signs of chafing deterioration abrasion or heat related damage Replace the wiring harness if a wire is broken ...

Page 33: ...rocedures refer to the airframe manufacturer s instructions 16 Examine all engine controls for general condition full travel and freedom of operation in accordance with the airframe manufacturer s instructions 17 Before flight make sure that all leaks and problems have been corrected or repaired Repair or replace all missing or damaged components identified by the airframe manufacturer s instructi...

Page 34: ... CAUSE THE ENGINE TO START AND THE PROPELLER TO TURN WHICH CAN LEAD TO DEATH OR SERIOUS INJURY OR A PROPELLER STRIKE NOTICE Copy the blank checklist and complete this checklist as a record of engine maintenance Put the completed checklist in the engine logbook 10 Hour Initial Engine Inspection Checklist Engine Model Number__________________ Engine Serial Number ______________ Date Inspection Done ...

Page 35: ...CH IS SET TO OFF AND THAT ALL POWER TO THE ENGINE IS DISCONNECTED ENSURE ALL OBJECTS PERSONNEL ARE CLEAR OF THE PROPELLER S ROTATIONAL ARC IF POWER IS ON A LOOSE OR BROKEN WIRE CAN CAUSE THE ENGINE TO START AND THE PROPELLER TO TURN WHICH CAN LEAD TO DEATH OR SERIOUS INJURY OR A PROPELLER STRIKE NOTICE Copy the blank checklist and complete the checklist as a record of engine maintenance Put the co...

Page 36: ...tion screen and oil filter for blockage Remove any blockage and clean the oil sump suction screen Identify the cause of any blockage and correct the problem Refer to the sections Oil Suction Screen Removal Installation and Oil Filter Oil Suction Screen Inspection in Chapter 12 10 EXAMINE THE OIL SUMP SUCTION SCREEN AND OIL FILTER ELEMENT FOR UNWANTED METAL PARTICLES A CLOGGED OIL FILTER AND OR SUC...

Page 37: ...other contamination Remove any dirt particulate sand or other contamination Refer to the Direct Drive Overhaul Manual for cleaning instructions Correct any discrepancies found before returning the engine to service Complete the operational ground check in accordance with Chapter 72 00 Look for leaks Identify and correct the cause of any leak Correct any problem and repair as necessary to make sure...

Page 38: ...KE NOTICE Copy the blank checklist and complete the checklist as a record of engine maintenance Put the completed checklist in the engine logbook 50 Hour Engine Inspection Checklist Engine Model Number__________________ Engine Serial Number ______________ Date Inspection Done ________ Inspection done by ______________________________ Aircraft Tachometer ____________________ Engine Time ___________...

Page 39: ...for damage and correct installation Replace damaged cowling or baffles Refer to the aircraft OEM procedures Champion Electronic Ignition System Remove spark plug connector nuts and examine spark plug cable leads and ceramics for corrosion and deposits Corrosion and deposits are evidence of leaking spark plugs or of improper cleaning of the spark plug walls or connector ends Clean the cable ends sp...

Page 40: ...tly Remove spark plug connector nuts and examine spark plug cable leads and ceramics for corrosion and deposits Replace spark plugs as necessary per Chapter 74 20 Corrosion and deposits are evidence of leaking spark plugs or of improper cleaning of the spark plug walls or connector ends Refer to the section Spark Plug Cleaning in Chapter 05 30 Clean the cable ends spark plug walls and ceramics Ref...

Page 41: ...en frayed or chafed or if a connector is broken or damaged Refer to the Direct Drive Overhaul Manual for replacement procedures Make sure that clamps are installed to keep the wiring harness in place Tighten or install any loose or missing clamps to keep the wires securely in place Engine Cylinders NOTICE During the first hours of service engines can have some leakage at the cylinder head This ini...

Page 42: ...nections between the exhaust system and exhaust ports of cylinder look for burnt paint around the spark plug and exhaust flange bosses or for light gray deposits near the leaks look for a warped exhaust flange which can cause a leak Exhaust leaks can cause damage to spark plugs ignition cables and the cylinder head Look for unusual discoloration on each engine cylinder If discoloration is found do...

Page 43: ...ents Results Notes Done General Correct any discrepancies found before returning the engine to service Complete the operational ground check in accordance with Chapter 72 00 Look for leaks Identify and correct the cause of any leak Correct any problem and repair as necessary to make sure the engine operates correctly to specifications Record all findings and corrective action in the engine logbook...

Page 44: ... TURN WHICH CAN LEAD TO DEATH OR SERIOUS INJURY OR A PROPELLER STRIKE NOTICE Copy the blank checklist and complete this checklist as a record of engine maintenance Put the completed checklist in the engine logbook 100 Hour or Annual Engine Inspection Checklist Engine Model Number__________________ Engine Serial Number ______________ Date Inspection Done ________ Inspection done by ________________...

Page 45: ...the Light Speed Installation and Operation Manual WARNING IF THE P LEAD IS DISCONNECTED THE MAGNETO WILL BE ON AND WILL ACTIVATE THE SPARK PLUG IF THE PROPELLER IS TURNED TO PREVENT INJURY MAKE SURE THAT THE P LEAD IS SECURELY ATTACHED TO THE CONDENSER STUD Make sure that the magneto to engine timing is correct Adjust the timing as necessary Refer to the Magneto to Engine Timing Check in Chapter 7...

Page 46: ...for carbon gum deposits and clogging Remove deposits as per the Direct Drive Overhaul Manual DO NOT ATTEMPT TO REPAIR A DAMAGED FUEL LINE REPLACE ANY FUEL LINE THAT IS CRACKED DENTED OR KINKED CRACKS CAN DEVELOP AT THE SIDE OF SHARP BENDS OR KINKS Examine solder joints at the end of fuel lines for cracks Replace cracked lines Examine the routing of fuel lines Make sure that the clamps securely sup...

Page 47: ...sical damage Make sure that they are tightly attached Repair or replace all of the damaged or missing parts of the cooling system in accordance with the airframe manufacturer s maintenance manual Engine Mounts Complete the Engine Mount Inspection Refer to the 100 Hour Engine Mount Inspection Procedure in Chapter 72 00 of this manual Inspection Item Comments Cylinders Complete the Cylinder Visual I...

Page 48: ...en the gasket screws per the torque values in the latest revision of the Service Table of Limits SSP 1776 Operational Test After all inspections and repairs are done complete the operational check in accordance with Chapter 72 00 Look for leaks Identify and correct the cause of any leak Correct any problem and repair as necessary to make sure the engine operates correctly to specifications Refer t...

Page 49: ...record of engine maintenance Put the completed checklist in the engine logbook 400 Hour Engine Inspection Checklist Engine Model Number__________________ Engine Serial Number ______________ Date Inspection Done ________ Inspection done by _____________________________ Aircraft Tachometer ____________________ Engine Time _______________________ Inspection Item Comments Results Notes Done Complete t...

Page 50: ...Comments Results Notes Done General Correct any discrepancies found before returning the engine to service Complete the operational ground check in accordance with Chapter 72 00 Look for leaks Identify and correct the cause of any leak Correct any problem and repair as necessary to make sure the engine operates correctly to specifications Record all findings and corrective action in the engine log...

Page 51: ...ection Checklist Engine Model Number__________________ Engine Serial Number ______________ Date Inspection Done ________ Inspection done by _____________________________ Aircraft Tachometer ____________________ Engine Time _______________________ Inspection Item Comments Results Notes Done Complete the 100 Hour Engine Inspection Refer to the section 100 Hour or Annual Inspection in this chapter Li...

Page 52: ...S INJURY OR A PROPELLER STRIKE NOTICE Copy the blank checklist and complete this checklist as a record of engine maintenance Put the completed checklist in the engine logbook 1000 Hour Engine Inspection Checklist Engine Model Number__________________ Engine Serial Number ______________ Date Inspection Done ________ Inspection done by _____________________________ Aircraft Tachometer_______________...

Page 53: ...HE METAL WHICH CAN CAUSE OIL FOAMING WHEN THE PART IS PUT BACK INTO SERVICE OBEY STANDARD SAFETY PRACTICES REGARDING THE HANDLING OF CLEANING MATERIALS AND THE USE OF PERSONAL PROTECTIVE EQUIPMENT NOTICE YO 233 B2A Series engines can be equipped with aluminum or magnesium oil sump or accessory housing Be aware of the type of components installed on your engine before cleaning completing maintenanc...

Page 54: ...ral spirits MIL PRF 680 kerosene or equivalent degreasing agent Clean with Scotch Brite or equivalent Remove debris with clean lint free wipes Stabilizers valve components starter drive fuel control inlet screen Mineral spirits MIL PRF 680 kerosene or equivalent degreasing agent Piston Mineral spirits MIL PRF 680 Safety Solvent or equivalent degreasing solvent Refer to the Piston Cleaning procedur...

Page 55: ...ing procedure in this chapter Lead deposits Refer to the Lead Deposit Removal procedure in this chapter Removal of gasket material MEK Acetone Naptha or equivalent Apply solvent to gasket material Use a wooden scraper to remove gasket material Wipe away all debris with clean lint free wipe Electrical connectors CR4 or equivalent Refer to contact cleaning solvent manufacturer s instructions Hartzel...

Page 56: ...ed Operate the grit blast gun as per the manufacturer s instructions 3 Unless otherwise specified in the manufacturer s instructions use approximately 35 to 45 psi 241 to 310 kPa of air pressure during grit blasting 4 Use compressed air and the vacuum cleaner to remove any debris and residue 5 After all cleaning is complete a Rinse the part in a petroleum solvent b Dry the part with an air blast t...

Page 57: ... B Soak for 10 minutes to loosen the hard carbon C Remove the component from the bath tank D Use a non wire bristle brush wooden plastic or phenolic scraper or grit blasting per the section Grit Blasting in this chapter to physically remove the hard carbon E Remove any remaining hard carbon from the component with a lint free wipe F Apply a spray coating of preservative oil on the component to pre...

Page 58: ... until there is no abrasive residue 6 Piston Cleaning CAUTION DO NOT USE A STEEL BUFFING BRUSH TO CLEAN THE RING LANDS AND SKIRT OF A PISTON DO NOT GRIT BLAST PISTON RING GROOVES OR PISTON SKIRTS THESE METHODS CAN STRETCH THE SIDES OF THE PISTON RING GROOVES AND ROUND OFF THE OUTER CORNER OF THE PISTON RING LANDS WHICH AFFECTS THE PISTON CONFIGURATION A Remove all oil or preservative oil accumulat...

Page 59: ...m or aluminum contact Technical Support at Lycoming Engines at the phone numbers in the front of this manual A Put the component fully immersed in mineral spirits or equivalent in a bath tank NOTICE For small steel parts cold dip tanks or a closed tank system can be used with NALCO 1704 B Remove the component from the bath tank C Remove any remaining soft carbon dirt or sludge from the component w...

Page 60: ...ts from the parts 2 Spray or brush the components with a hydrocarbon base solvent B To remove volcanic ash 1 Wear personal protective equipment gloves respiratory and eye protection 2 Per the aircraft manufacturer s instructions thoroughly remove the ash or particulate from the aircraft by hand brushing or air vacuuming Make sure that all ash is removed from the engine and cowling C Examine the in...

Page 61: ...acid which could harm the metal 12 Cleaning Method for Non Destructive Testing A Remove all traces of Paint Corrosion Gasket materials Smeared metal Oil Plating Grease Chemical residues Dirt B Use any of the following cleaning methods as long as it is not harmful to the component or its intended function Vapor degreasing Solvent degreasing Ultrasonic cleaning Chemical cleaning Aqueous based cleani...

Page 63: ...eth etc b Complete the Magnaflux and degauss procedure on the steel parts of the engine during the inspection c Complete the engine overhaul in accordance with the Direct Drive Overhaul Manual Disassemble and examine the engine Discard all parts that have damage discoloration cracks etc d Examine the crankshaft rod journals main journals counterweights camshaft lobes bearings gear teeth and all ot...

Page 64: ...ned metal accumulation is found identify and correct the cause before putting the engine back into service d Complete the Valve Train Overspeed Inspection procedure in this chapter e Complete the EIS Overspeed Inspection or Magneto Overspeed Inspection in this chapter f In the engine logbook record the overspeed incident and any inspection and corrective action Engine overspeed more than 10 in exc...

Page 65: ...remove them and complete the check of the compression load as specified in the latest revision of the Service Table of Limits SSP 1776 Replace any valve spring that is not within limits d Rotate the crankshaft by hand to see if the valve lift is uniform or equal for all cylinders See if valve rockers are free when the valves are closed Unequal valve lift is an indication of bent push rods Tight ro...

Page 66: ...evaluation and advisory on whether an engine repair or overhaul is necessary or 2 Complete the following in the field a Disassemble and clean the engine in accordance with the Direct Drive Overhaul Manual b Complete then inspection of the engine in accordance with the Direct Drive Overhaul Manual c During inspection of engine components carefully look for signs of detonation such as tuliped intake...

Page 67: ...mine the engine for hydraulic lock as directed below a Remove all cylinders and connecting rods in accordance with the Direct Drive Overhaul Manual b If all connecting rods are in compliance with the specified criteria in the Overhaul Manual reassemble the engine in accordance with the Direct Drive Overhaul Manual c If any connecting rod is not in compliance with acceptance criteria remove and dis...

Page 68: ...ection Per the airframe manufacturer s instructions thoroughly remove the ash or particulate from the aircraft by hand brushing or air vacuum Make sure that all ash is removed from the engine nacelle and cowling Wear personal protective equipment Examine the external engine cowling and nacelle for any particulate or ash residue Remove any particulate or ash residue per the airframe manufacturer s ...

Page 69: ...tion Replace the fuel filter if contamination is found Examine seals for damage and leaks Replace damaged or leaky seals Monitor oil temperature and pressure for indications of engine problems Clean the engine with high pressure air spray Be sure to clean the cooling fins on the cylinder In volcanic ash fall out or high sand or dust areas after the engine cools install inlet and exhaust covers to ...

Page 70: ...n in the Flight Manual or Pilot Operating Handbook NOTICE Circumstances which cause loss of oil pressure can be different which makes prediction of the extent of damage to the engine or future engine reliability difficult In case of oil pressure loss or engine operation with oil below the minimum operating level the most conservative action is to remove the engine disassemble and completely examin...

Page 71: ...rogression to engine failure Sudden rpm drop on impact to water tall grass or similar yielding medium where propeller damage does not usually occur 3 A propeller strike can occur at taxi speeds including instances of touch and go operations with propeller tip ground contact In addition propeller strikes also include situations where an aircraft is stationary and a landing gear collapse occurs caus...

Page 72: ...Inspection Checklist After Propeller Strike for YO 233 B2A Series Engines Engine Model Number Engine Serial Number Date Inspection Started Date Inspection Completed Sequential Task Additional Information Corrective Action Done Comments 1 Examine the propeller for extent of damage record condition of propeller Condition of Propeller Corrective Action Propeller satisfactory Repair propeller in accor...

Page 73: ...e FPI or subsequent oil flow 9 Remove and discard the existing crankshaft gear retaining bolt and lockplate Refer to the Crankshaft Disassembly procedure in Chapter 72 20 10 Examine the crankshaft Refer to the Crankshaft Inspection procedure and checklist in Chapter 72 20 11 Examine the crankshaft counter bored recess the alignment dowel especially at the base where it goes into the crankshaft the...

Page 74: ...Flange run out within acceptable limits use crankshaft Replace crankshaft 15 Measure the main bearing run out on the crankshaft Refer to the latest revision of Part I of the Service Table of Limits SSP 1776 for the main bearing run out tolerance Record the main bearing run out measurement Main bearing run out within acceptable limits use crankshaft Replace crankshaft 16 Measure the polished dimens...

Page 75: ...ch connecting rod Replace all connecting rods not in compliance with measurements in the latest revision of the Service Table of Limits SSP 1776 Reference 504 Squareness Measurement Connecting Rod 1 Connecting Rod 2 Connecting Rod 3 Connecting Rod 4 NOTICE The magnetic particle inspection must be done by a certified technician as per the latest revision of Service Instruction No 1285 20 Complete a...

Page 76: ...on the oil sump Record test results Use oil sump Replace oil sump 27 Complete the visual inspection and FPI on the engine mounts Record test results Use engine mounts Replace engine mounts 28 Complete the visual inspection and FPI on the accessory housing Record test results Use accessory housing Replace accessory housing 29 Complete the visual inspection and FPI on the oil pump impeller Record te...

Page 77: ...s of all engine mounted accessories including the propeller governor if installed etc for continued airworthiness instruction 36 Assemble and install the engine Install the propeller and test the engine Complete an Operational Ground Check of the engine In accordance with instructions in Chapters 72 00 and 72 10 37 Complete Field Run In if applicable and Engine Initiation Refer to the Field Run In...

Page 78: ...h can cause indications to be tightly closed and therefore missed during future inspections C Requirements for NDT Personnel Personnel who complete the Magnetic Particle and Fluorescent Penetrant Inspections on Lycoming engine components must be qualified and certified to a written procedure in accordance with NAS 410 Certification and Qualification of NDT personnel Also personnel who make the acc...

Page 79: ...engine C Refer to the airframe manufacturer s manual for fuel capacity 2 Oil Level Check DURING ENGINE OPERATION THERE ALWAYS MUST BE A SUFFICIENT SUPPLY OF OIL IN THE ENGINE FOR CORRECT ENGINE OPERATION IF YOU OPERATE AN ENGINE WITH INSUFFICIENT OIL ENGINE FAILURE CAN OCCUR REFER TO APPENDIX A OF THE YO 233 B2A ENGINE INSTALLATION AND OPERATION MANUAL FOR MINIMUM QUANTITY OF OIL IN FLIGHT A The o...

Page 80: ...AFT IS NOT TO BE IN FLIGHT UNUSUAL OIL CONSUMPTION IS INDICATION OF A PROBLEM SUCH AS OIL LEAKS OR CYLINDER MALFUNCTION IDENTIFY AND CORRECT THE CAUSE S OF THE INCREASED OIL CONSUMPTION A The maximum rate of oil consumption in quarts per hour is 0 006 X BHP X 4 7 4 B Usual oil consumption rates in quarts per hour are shown in Table 1 Table 1 Oil Consumption Performance 75 Rated 0 84 Max Qt Hr Econ...

Page 81: ...l to touch B Remove the oil level gauge dipstick assembly DO NOT OVER FILL THE ENGINE WITH OIL IT CAN CAUSE ENGINE DAMAGE C Measure the oil level Refer to the section Oil Level Check in this chapter D Add oil as necessary and measure the oil level until the oil level check shows that there is sufficient oil in the engine for the flight conditions E Install the oil level gauge dipstick rod securely...

Page 82: ... has not been flown for at least 25 hours in a 4 month period More frequent oil changes are recommended if the engine has been exposed to volcanic ash particulate sand dust debris or extreme weather conditions 8 Oil Change Procedure ENGINE OIL IS FLAMMABLE OBEY ALL FIRE HAZARD PRECAUTIONS DURING THE OIL CHANGE PROCEDURE NOTICE An oil sample must be collected during the oil change The oil change an...

Page 83: ... bottom of the oil sump since it may give false positive readings 1 After 1 3 of the oil has been drained from the engine s oil sump collect 1 to 2 oz 30 to 60 ml of oil into the clean sample vial 2 Identify the oil sample vial with a mark or label 3 Send the oil sample in the vial to the same laboratory that has been used in the past for spectrographical analysis to compare past results and ident...

Page 84: ...ached the Desired Oil Temperature listed in Appendix A of the YO 233 B2A Engine Installation and Operation Manual M Allow the engine to cool for 15 minutes N Examine the engine and nacelle for oil leaks Refer to the Oil Leak Check procedure in this chapter DISPOSE OF THE USED OIL AND CLEAN UP ANY SPILLED OIL OR FUEL IN COMPLIANCE WITH FEDERAL STATE AND LOCAL ENVIRONMENTAL REGULATIONS O Clean up an...

Page 85: ...rvicing A Metallic particles in the oil will require further examination since the metallic particles can be an early indication of wear or damage to engine components such as cylinders bushings piston pins etc Metallic particles herein include metal particulates and or chips flake hair like strands shavings etc B Identification of the nature of the metallic particles found in an oil filter elemen...

Page 86: ...admium zinc etc cannot be picked up with a magnet The visual inspection procedure is slightly different for oil filter elements and screens Visual inspection for oil filter element Visual inspection for oil pressure screen or oil suction screen Remove the oil filter element from the oil filter canister Drain all fluid oil through a strainer cloth or paper to remove oil from either the oil pressure...

Page 87: ...Table 5 identifies specific corrective action for the various findings The type of material Table 3 regardless of quantity and or the quantity and size of metallic particles Table 4 can help determine the corrective action Table 5 to be taken NOTICE Table 3 only applies to engines that use genuine Lycoming Parts Table 3 Guidelines for Identification of Metal Particulates and Chips Corrective Actio...

Page 88: ...lead chips chunks or balls are found complete Corrective Action 4 in Table 5 Aluminum flakes When placed in 50 solution of nitric acid and muriatic acid approximately 30 hydrochloric acid and water or a sodium hydroxide solution the aluminum particles bubble and fizz and form a black residue Crankcase Accessory housing Oil pump body Cylinder head Pistons Piston pin plugs Oil sump baffle Turbocharg...

Page 89: ...orrective Action 3 Pieces of metal that are chunks greater than 3 16 in 4 8 mm or chips smaller than chunks NOTICE A mixture of magnetic and nonmagnetic material can indicate valve or ring and piston failure NOTICE Remove the bottom spark plugs to identify a non conforming cylinder Corrective Action 4 1 4 teaspoonful or more of nonmagnetic plating with or without a copper tint could vary in sizes ...

Page 90: ...of metallic particles and metal has not gotten past the oil filter Possibly only one engine cylinder is damaged or spark plug is worn or damaged Corrective Action 5 If the cause of the metal contamination cannot be identified speak with the Lycoming Engines Product Support If there is unusual aluminum bronze or iron contamination in the oil make sure you have a full description of the engine model...

Page 91: ...and examine the oil filter d If the oil filter is clean install a new oil filter e Operate the engine in flight for 10 hours f Remove and examine the oil filter g If either the oil filter is clean resume the routine oil servicing schedule If chunks or more than 45 metallic particles are found ground the aircraft and proceed to Corrective Action 3 3 a Per sections in this chapter complete Oil Chang...

Page 92: ...ticles have spread to other parts of the engine If the contamination has spread to other parts of the engine proceed to Corrective Action 4 6 a Complete these procedures in Chapter 72 30 Cylinder Removal Piston Removal b Per the Connecting Rod Inspection Checklist in Chapter 72 20 examine the connecting rod bushing 7 c Complete these procedures in Chapter 72 30 Cylinder Removal Piston Removal a Pe...

Page 93: ...lest to the most complex possible causes NOTICE The Ref column includes reference to IOM for the YO 233 B2A Engine Installation and Operation Manual OHM refers to the Direct Drive Overhaul Manual A numeric entry such as 72 00 refers to a chapter in this manual Table 1 Fault Isolation Guide Problem Cause Corrective Action Ref Engine will not start or starts with difficulty Inactive battery Replace ...

Page 94: ...ition switch on and put the mixture control in IDLE CUT OFF 2 Fully open throttle and start the engine 3 If the engine does not start in 5 seconds shut down and do not try to start until the starter cools down 4 When the engine starts decrease throttle and advance the mixture control slowly to FULL RICH Faulty ignition wire 1 Examine the ignition harness for breaks and cracks 2 Replace faulty wire...

Page 95: ... instructions in the section Idle Speed Mixture Adjustment in Chapter 72 00 2 Readjust idler speed 72 00 Found only as follows High ambient temperatures Engine operating for a long time at low or idle rpm 1 Operate with cowl flaps in the full open position 2 Keep ground operation to a minimum 3 Operate with boost pump on as necessary 4 Complete the check of the vent return line for blockage Clean ...

Page 96: ...or fuel pressure regulator OHM Uneven cylinder compression 1 Complete the cylinder compression check 2 Complete the borescope inspection of low cylinder s to determine if further disassembly and repairs are necessary 72 30 Ignition leads Make sure all ignition leads are secure Fault in the ignition system 1 Remove the distributor block and examine leads using a high tension lead tester 2 Repair or...

Page 97: ...ure is extremely rich evident by excess black exhaust 1 Lean idle mixture Refer to instructions in the section Idle Speed Mixture Adjustment in Chapter 72 00 2 Readjust idle speed 72 00 Fuel pressure is set too high Adjust engine fuel pump Broken fuel pump drive Replace the fuel pump in accordance with airframe manufacturer s instructions OHM Engine will not shut off Faulty power switches Replace ...

Page 98: ...rame manufacturer s specifications Propeller is out of adjustment not reaching specified low pitch Adjust in accordance with propeller or airframe manufacturer s instructions Muffler s internal baffles are broken and blocking the exhaust outlet NOTICE Broken baffles can move around freely in the muffler The engine may turn static rpm s intermittently 1 Hit the muffler with a rubber mallet or soft ...

Page 99: ...if necessary OHM Incorrect type of fuel 1 Replace fuel with correct fuel 2 Also refer to Incorrect Fuel or Fuel Contamination in Chapter 05 50 IOM Appendix A Throttle lever is incorrectly adjusted Adjust the throttle lever in accordance with airframe manufacturer s instructions Insufficient combustion 1 Complete the cylinder compression check 2 Complete the borescope inspection to look for excessi...

Page 100: ... the air flow Engine hesitates misses Valve sticking Refer to Valve Sticking 05 50 Engine surges Low engine oil level Complete the check of the oil level 12 10 Faulty governor Leak test propeller governor Replace the propeller governor 72 20 OHM Incorrect propeller governor Make sure that the propeller governor isthe correct part number Breather is blocked Examine the breather for obstructions Rem...

Page 101: ...r the oil pressure relief valve Remove disassemble and clean the oil pressure relief valve OHM Damaged oil pressure relief seat Replace or repair the oil pressure relief seat OHM Blockage at inlet side of oil pump Remove and clean the oil suction screen and oil passage to the inlet side of the oil pump 12 10 Too much internal oil spill off Examine these area Loose or missing plugs in oil galley Pi...

Page 102: ...or incorrectly installed OR Cylinder barrels are glazed or worn too much 1 Complete the cylinder compression check 2 Complete the borescope inspection NOTICE Listen for a hissing sound around the rings which is an indication of air leaks at the breather entrance of the crankcase 3 Remove the cylinders replace the piston rings and deglaze the cylinder barrels 72 30 OHM Worn valve guides 1 Remove th...

Page 103: ...er modify relocate or eliminate any cooling baffles OHM Engine is operating excessively lean 1 Refer to Appendix C in the YO 233 B2A Engine Installation and Operation Manual for minimum fuel flows for various power settings and never lean below minimum fuel flows 2 Examine the combustion chamber for carbon deposits The absence of carbon deposits is evidence of operating the engine too lean IOM App...

Page 104: ...er or oil cooler lines are fully or partially blocked 1 Remove the oil cooler and oil cooler lines 2 Flush out in accordance with airframe manufacturer s manual Thermostatic bypass valve is not operating correctly or seating accurately 1 Replace thermostatic bypass valve 2 Replace the filter base if valve is not seating properly OHM Too much blow by 1 Complete the differential compression check in...

Page 105: ...l pressure Oil pressure incorrectly adjusted 1 Increase the oil pressure by turning the adjusting screw clockwise 2 Decrease the oil pressure by turning the adjusting screw counterclockwise 72 50 Incorrect weight of oil used Use the recommended viscosity of oil for the ambient temperature IOM Appendix A Oil passage is blocked from the pressure relief valve to the sump 1 Remove the pressure relief ...

Page 106: ...nance Manual Table 1 Cont Fault Isolation Guide Problem Cause Correction Steps Ref Too much noise or vibration Insufficient bearing lubrication 1 Supply the required oil 2 Clean or replace the oil hose clean the oil strainer Leak in engine intake or exhaust manifold Tighten loose connections or replace manifold gaskets as necessary ...

Page 107: ... 3 Make sure that all electrical switches circuit breakers Ignition Switch and the Fuel Selector Valve are in the OFF position 4 In accordance with the airframe manufacturer s instructions remove all cowling baffling and nacelle access panels that prevent engine removal USE CARE TO PREVENT DUST DIRT LOCKWIRE NUTS WASHERS OR OTHER FOREIGN MATTER FROM ENTERING THE ENGINE DURING ENGINE REMOVAL IF ITE...

Page 108: ...76 Safety the drain plug 16 Disconnect the throttle control in accordance with the airframe manufacturer s instructions 17 Remove the manifold pressure gage line and airframe fuel supply hoses in accordance with the airframe manufacturer s instructions 18 Refer to the airframe manufacturer s instructions to disconnect any accessory connections or to remove any external accessories to enable remova...

Page 109: ...any open lines 27 To prevent delays on engine re installation have materials and new spare parts on hand Refer to the YO 233 B2A Series Engine Illustrated Parts Catalog 3 Engine Installation Preparation Requirements To prevent delays on engine re installation have the following materials and new spare parts available YO 233 B2A Series Engine Illustrated Parts Catalog to replace any of these parts ...

Page 110: ...t all of the engine gages operate correctly C Make sure that the vent and breather lines are correctly installed and secured in accordance with the airframe maintenance manual D Install the cowling and all of the intercylinder baffles and airframe baffles IF YOU CANNOT GET A TEST CLUB YOU CAN USE THE REGULAR FLIGHT PROPELLER IF YOU USE THE FLIGHT PROPELLER MONITOR THE CYLINDER HEAD TEMPERATURE E U...

Page 111: ...empts complete a check of the idle linkage and look for loose connections which could cause erratic idling Also take into account weather conditions and field altitude which could affect the idle speed mixture adjustment 7 Engine Mount Inspection Procedure A Examine the engine mounts for cracks B Examine the engine mounts for looseness of the engine and mounting Tighten any loose hardware Refer to...

Page 113: ...ware fasteners are torqued correctly and to identify any oil leaks cracks and mechanical damage on the crankcase that must be corrected before putting the engine back into service IF A CRACKED CRANKCASE IS NOT REPLACED OIL CAN LEAK OUT OF THE CRANKCASE AND CAUSE ENGINE FAILURE B Examine the exterior surface of the crankcase for cracks and damage A crankcase with one or more cracks must be replaced...

Page 115: ... Figure 1 thoroughly for cracks leaks rust pitting and or damage Replace a damaged rusted pitted leaky or cracked cylinder per instructions in this chapter B Look for loose or damaged crankcase thru studs and cylinder hold down studs Replace with appropriate oversize studs per Appendix A C Look for loose or damaged spark plug Heli Coil inserts If a loose or damaged Heli Coil is found replace the H...

Page 116: ...initial inspection of the condition of the engine cylinders This procedure compares the static leak rate of the cylinder with the leak rate through an orifice of a specified range B The Cylinder Compression Check on the engine cylinders must be done at the following times or if the engine has any of these conditions After every 100 hours of engine operation or annual inspection Loss of power or un...

Page 117: ... of the gages to be connected to the differential compression tester are calibrated in accordance with the differential compression tester s manufacturer s specifications 3 Refer to the differential compression tester s manufacturer s instructions to ensure the tester operates correctly C Cylinder Compression Check Procedure NOTICE Make sure the differential compression tester has been calibrated ...

Page 118: ...rn the crankshaft by hand in the direction of propeller rotation to put the piston in a position as close to Top Dead Center TDC on the compression stroke as possible 6 Install the threaded end of an adapter with a coupling end in the spark plug hole of the cylinder to be tested 7 Make sure that the air valve on the differential compression tester is in the CLOSED position CAUTION BEFORE CONNECTIO...

Page 119: ...e sure that the piston rings are seated 16 Record the pressure reading on the engine cylinder pressure gage The difference between the engine cylinder pressure gage reading and the pressure shown on the air supply pressure gage reading is the amount of leakage through the cylinder 17 The minimum approved engine cylinder pressure reading is 60 psi 414 kPa Maximum approved leakage is 25 20 psi 138 k...

Page 120: ...cessary corrective action Difference of 5 psi 34 kPa or less between engine cylinders Pressure readings for all engine cylinders must be nearly equal Satisfactory No corrective action necessary Difference of 6 to 15 psi 41 to 103 kPa between engine cylinders Repeat the Cylinder Compression Check after the next 10 hours of engine operation A valve can reseat itself and show satisfactory compression...

Page 121: ...nder or send the engine cylinder to an authorized vendor to replace the valve seat 4 Intercylinder Baffle Inspection NOTICE This inspection can be done while the intercylinder baffles are installed on the engine A This inspection is done during the visual inspection to look for premature cylinder deterioration and make sure that intercylinder baffles are correctly fitted and installed The intercyl...

Page 122: ...ticking section in this chapter 6 Worn piston rings or worn cylinder barrel 7 Insufficient combustion C Cylinder Borescope Inspection Procedure 1 Remove a top spark plug from each cylinder per the Spark Plug Removal procedure in Chapter 74 20 2 Put the piston at bottom dead center on the power stroke 3 Install the borescope through the vacant top spark plug hole on the engine cylinder and examine ...

Page 123: ... for cracks and erosion on the intake valve face Cracks or erosion on the intake valve face Replace the intake valve Examine the cylinder bore for scoring rubbing or corrosion Scoring or piston rub or corrosion on cylinder bore Remove and examine the engine cylinder Look for excessive oil in the cylinder Excessive oil in the cylinder Remove and examine the engine cylinder Remove and examine the oi...

Page 124: ...1485 and Service Letter L197 for additional details NOTICE The Gage ST 71 is used to examine parallel type valves on engine cylinders Although the Gage ST 71 and a feeler gage can be used to measure valve stem movement a modified ST 71 Figure 4 and a dial indicator are a faster and easier means to measure valve stem movement valve guide wear and carbon build up per this procedure Figure 4 Details ...

Page 125: ...ward the intake side enough to remove the exhaust rocker assembly Figure 5 YO 233 B2A Engine Valve Components 7 Remove the exhaust rocker assembly 8 Remove the valve stem cap from the exhaust valve 9 Turn the crankshaft to position the piston at the bottom of the compression stroke 10 Insert about 8 ft 2 4 m of 3 8 inch nylon rope through the spark plug hole turn the crankshaft until the piston mo...

Page 126: ...t side push rod assembly shroud tube hydraulic lifter socket and plunger assembly 16 Remove the washer and seal from the cup in the exhaust side tappet bore of the crankcase and shroud tube seal from the engine cylinder Discard the seals NOTICE Do not confuse valve spring seats with valve seats valve spring seats Figure 5 are metal disks installed on the ends of the valve springs in the rocker box...

Page 127: ...haust valve stem and Gage Adapter ST 71 8 against the upper exhaust valve spring seat as far as they will go 22 Put the blade of a screwdriver in the area between the exhaust valve spring and Gage ST 71 23 Use the screwdriver to push the valve the maximum distance away from the dial indicator as shown in Figure 8 24 Move the dial indicator toward the adapter post until the indicator is preloaded a...

Page 128: ...to the latest revision of Service Instruction SI 1011 for plunger assembly inspection guidelines 33 Apply engine oil mixture 15 pre lubricant STP or equivalent and 85 SAE No 50 mineral base aviation grade lubricating oil to the new seal and shroud tube seal Figure 5 34 Install a new seal and the washer into the cup in the exhaust side tappet bore of the crankcase 35 Assemble the new shroud tube se...

Page 129: ...his step 49 Enable power to the engine 50 Complete the Operational Ground Check in Chapter 72 00 51 Record all of the results in the 1000 Hour Inspection Checklist for YO 233 B2A Engines in Chapter 05 20 7 Cylinder Removal A Disable all power to the engine and disconnect the engine wiring harness from the airframe B If not already done Remove airframe components to enable cylinder removal Airframe...

Page 130: ...drain tube assembly 2 Disconnect the hose from the nipple 3 Disconnect the drain tube fitting from the engine cylinder 4 Remove and discard the hose 5 Remove the oil drain tube assembly from the cylinder 6 Examine the oil drain tube for cracks or damage 7 Replace a cracked or damaged drain tube assembly Figure 12 Oil Drain Tube NOTICE Remove the cylinders by firing order 1 3 2 4 Figure 13 Remove e...

Page 131: ... in the same cylinder E Remove the screws from the rocker box cover Figure 1 NOTICE A silicone rocker box cover gasket can be reused if it is not damaged F Remove the rocker box cover and gasket Discard a cork gasket G Turn the crankshaft to put the piston at TDC of the compression stroke of the cylinder to be removed With the piston in this position both intake and exhaust valves are closed and t...

Page 132: ...Oil Ring and Cylinder Fins CAUTION AS EACH CYLINDER IS SEPARATED FROM THE CRANKCASE CATCH AND HOLD THE PISTON TO PREVENT IT FROM FALLING AGAINST THE CRANKCASE AND BEING DAMAGED P Remove the cylinder Q Remove and discard the cylinder base oil seal ring from the cylinder Figure 17 CAUTION IF A CYLINDER IS NOT TO BE IMMEDIATELY INSTALLED ON THE CRANKCASE INSTALL TORQUE HOLD DOWN PLATES ST 222 TO MAIN...

Page 133: ...STON RINGS IN THE NEXT STEP USE CARE NOT TO SCRATCH THE PISTON D Start from the top down use the Piston Ring Expander P N 64713 to remove the two top compression rings and the oil regulating piston expander ring Figure 18 9 Connecting Rod Removal CAUTION DO NOT RE USE THE CONNECTING ROD BEARINGS BOLTS AND NUTS NOTICE If the two nuts in the connecting rod cap cannot easily be removed use a soft pla...

Page 134: ...valve springs and spring seats Corrective Action Replace any broken or worn parts Figure 5 Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4 Examine the intake and exhaust valve seats for looseness scoring pitting damage or non conformities Look for cracked or eroded valve seat bores Corrective Action If a valve seat is loose scored pitted defective or damaged valve seats either replace the cylinder or ...

Page 135: ... Look for discolored burnt paint or scored cylinder barrel bores Look for blistered paint on the cylinder barrel Corrective Action Replace the cylinder if the cylinder barrel bores are scored or the paint is discolored burnt blistered Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4 Examine the threads in all threaded holes in the cylinder for debris or damage Corrective Action Use the correct size bot...

Page 136: ...linder 1 Cylinder 2 Cylinder 3 Cylinder 4 Look for broken bent or straightened or pitted cylinder head fins Refer to the Visual Cylinder Inspection in this chapter Corrective Action Replace any cylinder that has unacceptable cylinder head fins Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4 Look for cracks in the cylinder head Measure the diameter of the cylinder head at several points to identify any...

Page 137: ...r 3 Cylinder 4 Look for scratches in the honed surface of the cylinder wall or cylinder bore Corrective Action Hone the cylinder to remove the scratches Refer to the latest revision of the Service Table of Limits SSP 1776 for dimensions and limits Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4 Make sure there is not any cylinder head to barrel flange movement Corrective Action Replace any cylinder th...

Page 138: ...e Corrective Action Replace all loose or damaged spark plug Heli Coil inserts with oversize inserts per the Heli Coil Replacement procedure in this chapter Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4 Examine studs on the cylinder head for looseness of damage Corrective Action Replace all loose or damaged studs with the next higher applicable oversize studs Cylinder 1 Cylinder 2 Cylinder 3 Cylinder...

Page 139: ...on ring lands and grooves Piston pin holes Piston pin whole bosses Look for deposits or damage Complete the Piston Cleaning procedure in Chapter 05 30 NOTICE Surface distortion can be an indication of detonation or pre ignition Cylinder 1 Cylinder 2 Cylinder 3 Cylinder 4 After Cleaning Look for cracks on the piston head or skirt Replace the piston if a crack is found Look for bent or broken lands ...

Page 140: ... of the piston between the top and second compression ring grooves at a right angle to the piston pin hole Figure 22 Actual Measurement SSP 1776 Measure the diameter approximately 1 8 in above the bottom of the piston skirt at a right angle to the piston pin hole Figure 22 Actual Measurement SSP 1776 Subtract the diameter approximately 1 8 in above the bottom of the piston skirt from the Average C...

Page 141: ... straight edge Figure 23 Top piston compression ring Actual Measurement SSP 1776 Second piston compression ring Actual Measurement SSP 1776 Piston oil ring Actual Measurement SSP 1776 Measure the piston ring end gap with feeler gauges Complete the Piston Ring End Gap Check in this chapter Top piston compression ring Actual Measurement SSP 1776 Second piston compression ring Actual Measurement SSP ...

Page 142: ... OR SCORE THE PISTON OR CYLINDER BORE 1 Lubricate the piston ring piston and cylinder bore with a light coating of a mixture of 15 pre lubricant STP or equivalent and 85 SAE 50 mineral base aviation grade lubricating oil unless otherwise directed per the latest revision of Service Instruction No SI 1059 2 Put one of the piston rings in the cylinder in which it will be used 3 To square the piston r...

Page 143: ...ore connecting rod replaced Examine the mating face of the connecting rod and its cap face for fretting Figure 24 If fretting is found replace the connecting rod assembly o No fretting o Fretting found connecting rod replaced Use a 6 power magnifying glass minimum or bench microscope to examine the critical areas on the connecting rod identified in Figure 24 for galling If galling is found replace...

Page 144: ...connecting rod bushing installed in the connecting rod on both sides of the connecting rod Examine the ID of the connecting rod bushing for a visible split line Refer to the latest revision of Service Bulletin No SB 630 for inspection instructions and any additional details Replace the bushing as necessary per the Connecting Rod Bushing Replacement procedure in this chapter Connecting Rod 1 Accept...

Page 145: ...t class except S weight rods service rods can be used with either A or E weight rods depending on parts availability Record the weight code of each connecting rod in this checklist 1 Assemble and torque each connecting rod with acceptable bearings per instructions in the Connecting Rod Installation section in this chapter 2 Measure the inside diameter of the bearing in each connecting rod and reco...

Page 146: ...vice limit per the Connecting Rod Inspection Checklist for TEO 540 EXP22 Engines If replacement bushing is Lycoming P N LW 13923 which must be burnished after installation refer to the latest revision of Service Instruction No 1575 A Clamp the connecting rod on the Connecting Rod Bushing Replacement Block P N 64597 in such a manner that the small bushing in the rod is in alignment with the hole st...

Page 147: ...RNISH CONNECTING ROD BUSHING P N 01K28983 THESE BUSHINGS ARE NOT DESIGNED TO BE BURNISHED AFTER INSTALLATION BURNISHING MAY RESULT IN DAMAGE TO BUSHING P N 01K28983 G Examine the bushing after installation to make sure the bushing is flush to 0 020 in 0 508 mm below the connecting rod surface Figure 28 on both sides of the connecting rod H Remove the connecting rod from the holding block and compl...

Page 148: ...0 in the bearing holes in the connecting rod C Pull the arbors through the sleeves D Install the gage arm on the arbor as shown in Figure 30 E Turn the adjusting screw on the gage arm until it just touches the arbor F Use the wing nut to lock the adjusting screw G Make sure the adjusting screw just touches the arbor Figure 30 Parallelism Check of Connecting Rods Figure 31 Squareness Check of Conne...

Page 149: ...n NOTICE Each connecting rod is identified by a letter A E S etc as a designation for weight class All of the connecting rods installed on the crankshaft must be of the same weight class except S weight rods service rods can be used with either A or E weight rods depending on parts availability A Ensure that all of the connecting rods have the same weight class letter B Apply specified lubricant t...

Page 150: ...n the connecting rods and caps point down toward the oil sump CAUTION CORRECT INSTALLATION OF THE NEW NUT ON EACH NEW CONNECTING ROD BOLT IS NECESSARY FOR CORRECT CONNECTING ROD ASSEMBLY EACH CONNECTING ROD NUT HAS TWO DIFFERENT SURFACES ONE SURFACE IS FLAT AND THE OTHER HAS A RAISED LIP BE SURE TO INSTALL EACH NUT ON THE CONNECTING ROD BOLT WITH THE FLAT FACE TOUCHING THE ROD THE RAISED LIP SURFA...

Page 151: ...new piston rings For new piston rings refer to the YO 233 B2A Illustrated Parts Catalog to identify the correct new piston rings to be installed on the piston New piston rings are shipped from Lycoming with the piston oil ring and the inner expander ring assembled The inner expander ring must be separated from the piston oil ring before installing them on the piston B Apply a generous coating of a...

Page 152: ... in Chapter 05 30 If a new piston or piston pin is installed use a pin that will give a palm push fit at 60º to 70ºF 15º to 20ºC B Apply lubricant specified in the latest revision of Service Instruction No SI 1059 to the inside diameter of the connecting rod bushing the outer diameter of the piston pin and the inside diameter of the piston pin hole CAUTION DO NOT ATTEMPT TO TURN THE CRANKSHAFT UNL...

Page 153: ...strol Contractor Special NLGI 1 to the intake valve stem or other lubricant identified in the latest revision of Service Instruction No SI 1059 2 Install a serviceable intake valve in the valve guide Figure 15 through the cylinder barrel 3 Put the cylinder on a Cylinder Block P N 64526 2 or equivalent 4 Install the valve spring seats and valve springs Figure 15 5 Compress the intake valve springs ...

Page 154: ...linder on the engine per the Cylinder Installation procedure in this chapter 20 Cylinder Installation NOTICE Before cylinder installation make sure that the connecting rod bushing was examined per the Connecting Rod Inspection Checklist for YO 233 B2A Engines in Chapter 72 20 Use a cylinder kit when installing a new cylinder When installing a removed cylinder be sure you are installing the correct...

Page 155: ...essor 64559 to install the cylinders Figure 38 as follows 1 Assemble the Piston Ring Compressor 64559 over the top piston rings and install the correct cylinder over the piston on the corresponding connecting rod pushing the Piston Ring Compressor ahead with the cylinder barrel Figure 39 2 As the cylinder barrel approaches the crankcase catch the Piston Ring Compressor 64559 as it drops off the pi...

Page 156: ...r these nuts is optional Figure 40 Sequence of Tightening Cylinder Base Hold Down Nuts 4 Use the same sequence shown in Figure 40 complete a torque check to 50 ft lb 68 Nm for all 1 2 in nuts on the cylinder base studs 5 Tighten both ends of the free thru studs at the same time at the all locations Make sure all thru studs have at least 1 1 2 threads above attaching nuts at both ends 6 Make sure a...

Page 157: ... both installed plunger assemblies and hydraulic sockets to their lowest position in the tappet bores in the crankcase 3 Apply engine oil mixture 15 pre lubricant STP or equivalent and 85 SAE No 50 mineral base aviation grade lubricating oil to all four of the shroud tube seals two for each shroud tube 4 Install one shroud tube seal and the washer into the cups in the tappet bores of the crankcase...

Page 158: ...ide the rocker shaft through the valve rocker assemblies and bushings to seat the valve rockers in place 7 Install the thrust buttons one on each end of the valve rocker shaft 8 Make sure the valve rocker assemblies are in the correct position on the intake and exhaust valves 9 Measure the clearance between the valve rocker and cylinder head Refer to the latest revision of the Service Table of Lim...

Page 159: ...ker box cover gasket is installed torque the rocker box cover screws to 50 in lb 5 6 Nm Do not reuse cork gaskets K Examine the silicone rocker box cover gasket to make sure it is intact and not deformed or damaged Replace as necessary L Install the silicone rocker box cover gasket and rocker box cover with screws on each rocker box Torque the screws to 35 in lb 4 0 Nm M Remove the vented plug fro...

Page 160: ...ust Engines Figure 50 Intercylinder Baffle Installed on Three Fins 3 Put a baffle retainer in place between the cylinders and use a cotter pin puller to pull the retainer hook through the slot in the retainer The retainer is forced down until the hook comes above the surface of the retainer far enough to be engaged over the bridge between the slots in the retainer 4 Ensure the intercylinder baffle...

Page 161: ... 53 Oil Drain Tube Figure 54 Oil Drain Tubes Clamps and Fittings 3 Install and tighten a hose clamp on the hose as follows for Cylinder Nos 1 and 2 face towards the front of the engine for the remaining cylinders install the hose clamp face towards the rear of the engine Figure 54 4 Connect the oil drain tube to the elbow fitting at the cylinder with a flange nut Torque the nut per instructions in...

Page 162: ...urce to correct the problem Refer to the latest revision of Service Bulletin No SB 480 for any additional details B If the source of the oil contamination cannot be found or corrected complete the following procedures in Chapter 12 10 1 Replace the oil filter more often after every 25 hours of operation instead of after every 50 hours of engine operation 2 Complete an oil change after every 25 hou...

Page 163: ...LVE THROUGH THE GUIDE K Install the valves that are satisfactory in the corresponding position from where valves were removed Refer to the Intake Valve Installation and Exhaust Valve Installation procedures in this chapter L Install the valve springs and valve spring seats Figure 15 M Remove and clean the hydraulic lifter and remove all oil N Examine the lifter for any malfunction O Clean the inne...

Page 164: ... this area H Complete the Cylinder Cleaning procedure in Chapter 05 30 I Lubricate the internal cylinder barrel thoroughly with SAE 50 engine oil or a rust preventative oil that conforms with MIL C 6529 NOTICE If step wear is found inside the cylinder barrel measure it using the dial bore gage used to measure cylinder diameter If the depth of the step wear is less than 0 0025 in 0 0635 mm remove t...

Page 165: ...8 Removing Tool P N 64595 3 Examine the removed Heli Coil to make sure it is not 0 010 in oversized Figure 57 If the removed Heli Coil is 0 010 in oversized replace the cylinder 4 Apply of coat of grease liberally to the Bottom Tap 64596 1 Figure 59 5 If the Heli Coil insert is replaced while the cylinder is installed on the engine take precautions to prevent metal shavings from falling into the c...

Page 166: ...rn from the end of the coil on the new 0 010 in oversized Heli Coil insert g Use the Inserting Tool P N 64594 Figure 60 to install the new 0 010 in oversized Heli Coil insert into the spark plug hole on the cylinder head Be sure that the first coil engages with the first thread h Continue to turn the Inserting Tool P N 64594 When the face of the sleeve on the tool is 1 16 inch away from the face o...

Page 167: ... sleeve with a plastic mallet to make a slight chamfered edge around the periphery of the tapped hole 4 Remove the adjusting screw stop nut on the Expanding and Staking Tool P N 64593 and remove this tool and its expanding mandrel 5 Use needle nose pliers to break off the tang at the notch of the newly installed 0 010 in oversized Heli Coil insert 13 In the engine logbook record replacement of the...

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Page 169: ...the engine as per instructions in the YO 233 B2A Engine Installation and Operation Manual 3 Run up the engine to 2000 rpm 4 Record the oil pressure reading 5 If the oil pressure is out of tolerance turn off the engine 6 To increase oil pressure use a screwdriver in the screw slot to turn the oil pressure adjustment screw on the oil pressure relief valve clockwise Figure 1 7 To decrease oil pressur...

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Page 171: ...ocedure A Look for defects in engine mounted accessories such as pumps B Make sure the fuel pump and any attached accessories are attached securely at the correct torque Refer to the latest revision of the Service Table of Limits SSP 1776 C Make sure that the alternator support bracket and mounting are tight D Refer to the latest revision of the Service Table of Limits SSP 1776 for torque values a...

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Page 173: ...ces 2 Heat damaged or burn wire 3 Vibration damage or chafing 4 Cracked insulation 5 Arcing 6 Insulation delamination F To replace damaged cables or clamps refer to the aircraft manufacturer s instructions G Examine the terminals for correct installation tightness and cleanliness Clean any dirty terminal tighten terminals as per the torque values in the latest revision of the Service Table of Limi...

Page 174: ...Table of Limits SSP 1776 5 Alternator Belt Tension Adjustment A On the adjusting link use the slot Figure 1 to adjust the alternator belt tension Alternator Belt Figure 1 6 Starter Ring Gear Support Replacement Procedure A Remove the propeller from the engine in accordance with the airframe manufacturer s instructions B Remove the starter ring gear support assembly Figure 2 C Install a new starter...

Page 175: ...enance procedure Evidence of dust or other solid material in the ducts is indicative of inadequate filter care or of a damaged filter NOTICE If there is volcanic ash dust do not touch with bare hands do not clean with water Refer to the section Volcanic Ash Particulate Contamination in Chapter 05 50 of this manual C If there is dust or other solid material in the air ducts remove the dust and cont...

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Page 177: ...al 2021 Avco Corporation All Rights Reserved 73 00 February 2021 Page 157 YO 233 B2A Engine Maintenance Manual 73 00 ENGINE FUEL AND CONTROL GENERAL 1 System Description A Refer to the YO 233 B2A Engine Installation and Operation Manual ...

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Page 179: ... fuel inlet strainers Always remove from the inlet side DO NOT RETURN THE ENGINE TO SERVICE UNLESS THE ENGINE IS OEPRATING CORRECTLY AND DOES NOT HAVE ANY LEAKS Look for any fuel leaks Identify and correct the cause of any fuel leak Operate the engine and look for leaks Identify and correct the cause of any leak or malfunction If leaks or malfunctions were found and corrected operate the engine ag...

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Page 181: ...to Chapter 74 20 Replace the spark plugs remove and install As needed Refer to Chapter 74 20 Examine spark plugs and ignition leads As needed Refer to Chapter 74 20 Examine the spark plug port seals to Complete the check of the Heli coils As needed Refer to Chapter 74 20 Clean the spark plugs Every 100 hours of engine operation Refer to Chapter 74 20 Reset the spark plug gap Every 100 hours of eng...

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Page 183: ...Examine the ignition lead connections Make sure the ignition lead connections are secure C Tighten the leads if any connections are loose D Make sure the ignition lead mounting clamps are tight 2 Remove the Spark Plug A Make sure that the power is disconnected from the engine B Make sure that the engine is cool to the touch C Identify and tag the location of all the spark plugs Figure 1 D Hold the...

Page 184: ...fine wire ground and center electrodes as shown in figures in Table 1 show the level of wear indication and condition of the spark plug Under usual conditions the electrode wear is caused by high voltage sparking and corrosive gases formed during combustion Table 1 General Spark Plug Wear Replacement Guidelines Spark Plug Findings Condition of Fine Wire Ground Electrode on Spark Plug Condition of ...

Page 185: ...rk plug core temperatures are sufficiently hot to activate the lead scavenging agents to prevent lead deposits on the spark plugs and exhaust valve stems Operate the engine at the specified operating temperature to prevent low temperature operation Use oil cooler baffles to keep the oil temperature from decreasing during winter flight Do not do low power altitude changes or low power landing appro...

Page 186: ...spark plug locations when the operational ground check indicates evidence of spark plug fouling A Remove all of the spark plugs Refer to the Remove the Spark Plug procedure in this chapter B Examine each spark plug and ignition lead Refer to the Examine Spark Plugs and Ignition Leads procedure in this chapter C Clean acceptable spark plugs Refer to the Clean the Spark Plugs procedure in this chapt...

Page 187: ...OR D Thread the spark plug by hand into the engine cylinder head within one to two threads of the gasket If the spark plug cannot be screwed in this far clean the cylinder or spark plug threads E Rotate the socket to tighten the spark plug in place F When the B nut thread makes contact with the spark plug threads push the ferrule against the spark plug while turning the B nut clockwise G Continue ...

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Page 189: ...ion system for the YO 233 B2A This system consists of a single magneto P N 66GP 0RANN ignition harness P N 67P20440 and a single Light Speed Engineering LLC Plasma III kit P N 66K29678 Y Refer to the latest revision of Service Letter No L283 for additional information Convert the Engine from the Champion EIS Ignition System to the Light Speed Plasma III and Magneto Ignition System 1 Remove the Cha...

Page 190: ... your thumb over the spark plug hole and turn the crankshaft in the direction of normal rotation until there is pushback pressure at the spark plug hole NOTICE Some timing lights operate in the reverse manner than identified herein The light comes on when the contact points open Refer to your timing light instructions F Connect the timing light leads to the appropriate magneto condenser terminals ...

Page 191: ...o to Engine Timing Adjustment Procedure in this chapter J If the magneto to engine timing is within tolerance or after the Magneto to Engine Timing Adjustment Procedure has been completed 1 Remove the timing light leads from the magnetos and grounding source 2 Attach the P Leads to the condenser terminal of each magneto with the nut and a new lock washer Torque the nut to 13 to 15 in lb 1 5 to 1 7...

Page 192: ...gurations are different between magneto suppliers This procedure applies to Slick magnetos only Refer to the manufacturer s instructions for other types of magnetos A Magneto Removal 1 Disconnect the ignition harness cap from the magneto per the Ignition Harness Removal procedure in Chapter 74 20 2 Disconnect any other wires connected to the magneto 3 Hold the magneto and remove the nuts lock wash...

Page 193: ... block 9 If not already done turn the crankshaft in the direction of normal rotation until the correct advance timing mark on the starter ring gear support assembly aligns with the reference point on the engine Figures 1 or 2 10 Apply Lubriko grease to the mating flange and install a new gasket on the mating flange of the magneto 11 Remove the timing pin Figure 4 and install the magneto on the eng...

Page 194: ...f the magneto harness 17 Connect the harness cap to the respective magneto with three screws shown in Figure 6 Tighten the three screws until all screws are touching the harness cap to ensure that there is an even gap around the cap 18 Torque the three screws to 18 to 20 in lb 2 0 to 2 3 Nm in the sequence shown in Figure 7 as a final torque Figure 6 Torque Sequence for Screws on Magneto Harness C...

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