TEO-540-C1A Engine Maintenance Manual
© 2018 Avco Corporation. All Rights Reserved
05-30
November 2018
Page 39
TEO-540-C1A Engine Maintenance Manual
Figure 1
Threads in the Crankshaft Counterbore
C.
Clean the threads of the recessed counterbore on the crankshaft as follows:
(1)
Use the correct sized undamaged bottoming tap for a 5/16-24 thread size. Do not use an
oversized tap.
CAUTION
TO PREVENT MAKING THE THREADS IN THE CRANKSHAFT
COUNTERBORE TOO LARGE, USE THE CORRECTLY SIZED TAP.
IF THE INCORRECT TAP IS USED, THE BORE CAN BE MADE TOO
LARGE TO CORRECTLY ENGAGE THE THREADS ON THE
CRANSKHAFT GEAR BOLT WHEN THE CRANKSHAFT TRIGGER
GEAR ASSEMBLY IS INSTALLED ON THE CRANKSHAFT. IF THE
BOLT THREADS ARE TOO LARGE, DISCARD THE CRANKSHAFT
AND REPLACE IT WITH A NEW CRANKSHAFT.
(2)
Install the tap into the recessed counterbore on the crankshaft.
(3)
Turn the tap as necessary to clean the threads.
(4)
Remove the tap.
(5)
Flush the crankshaft counterbore threads with mineral spirits (MIL-PRF-680) or
equivalent or Stoddard Solvent, or equivalent solvent to remove any debris.
(6)
Dry the crankshaft counterbore threads with compressed air.
D.
Examine the threads in the crankshaft counterbore (Figure 1). If the threads are worn,
stripped, galled, or damaged, send the crankshaft to Lycoming Engines for repair.
4.
Crankshaft Trigger Gear Assembly Cleaning
A.
Soak the crankshaft trigger gear assembly in mineral spirits (MIL-PRF-680) or equivalent or
Stoddard Solvent, or equivalent solvent.
B.
Remove all dirt and debris from the crankshaft trigger gear assembly with a lint-free wipe.
C.
Dry with compressed air.
D.
Complete the “Crankshaft Counterbore Cleaning” procedure in this chapter.
