Piper PA-28-161, Maintenance Manual

Page: 1017 / 1104

CHART 2 (Sheet 1 of 2)
RECOMMENDED NUT TORQUES
PIPER AIRCRAFT, INC.
PA-28-161, WARRIOR III
MAINTENANCE MANUAL
PAGE 3
Nov 30/06 5G5
91-10-00
TORQUES: The impor tance of correct application can not be
overemphasized. Undertorque can result in unnecessary wear of nuts and
bolts as well as the parts they are holding together. When insufficient
pressures are applied, uneven loads will be transmitted throughout the
assembly which may result in excessive wear or premature failure due to
fatigue. Overtorque can be equally damaging because of failure of a bolt or
nut from overstressing the threaded areas. The following procedures should
be followed to assure that the correct torque is applied:
1.
Self-Locking Fasteners - Add the friction torque from Chart “A” for sizes 8
through 7/16 to the recommended torque from Chart “B” to get the final
torque. This would be the actual reading on the torque wrench. To
determine friction drag torque for sizes 1/2 through 1 1/4, turn the nut fully
on to the bolt and determine the torque required to turn the nut. Add this
friction drag torque to the torque given in Chart “B”.
2. Castellated and Non-Self Locking Nuts - Use only the torque given in
Chart “B”. Unless otherwise specified, when castellated nuts are used
with a cotter pin on moving joints, do not torque the nut. Turn the nut onto
the bolt until proper grip is established and alignment with the cotter pin
hole is achieved. Then install the cotter pin.
GENERAL REQUIREMENTS.
1.
Calibrate the torque wrench periodically to assure accuracy. Recheck
frequently.
2. Ascertain that the bolt and nut threads are clean and dry (unless
otherwise specified by the manufacturers.) If the bolt or nut is required to
be lubricated prior to tightening, the torque range should be reduced 50
percent.
3. Use a bolt long enough to prevent bearing loads on the threads. The
complete chamfer or end radius of the bolt or screw must extend through
the nut.
4. Unique torques specified in the text of this manual supercede the torques
given in Charts “A” and “B”.
5. Refer o the latest revision of Lycoming Service Table Limits, SSP1776, for
torques on parts used on Lycoming engines.
6. A maximum of two AN960 washers may be added under bolt heads or
nuts to correct for variations in material thickness within the tolerances
permitted.
7. Self-Locking Fasteners - Limitations of the use of self-locking nuts, bolts
and screws including fasteners with non-metallic inserts are as follows:
A. Fasteners incorporating self-locking devices shall not be reused if
they can be run-up using only fingers. They may be reused if hand
tools are required to required to run them up providing there is no
obvious damage to the self-locking device prior to installation.
B. Bolts 5/16 inch diameter and over with cotter pin holes may be used
with self-locking nuts. Nuts with non-metallic locking devices may be
used in this application only if the bolts are free from burrs around
the cotter pin hole.
C. Do not use self-locking nuts at joints which subject either the nut or
bolt to rotate.
D. Never tap or rethread self-locking fasteners. Do not use nuts, bolts
or screws with damaged threads or rough ends.
CHART A
BOLT FRICTION DRAG TORQUE (IN. -LB.)
SIZE Coarse Fine
8 15 --
10 18 18
1/4 30 15
5/16 60 60
3/8 80 80
7/16 100 100
CHART B
COARSE THREAD SERIES
BOLTS
Steel Tension
AN 3 THROUGH AN 20
AN 42 THROUGH AN 49
AN 73 THROUGH AN 81
AN 173 THROUGH AN 186
MS 20033 THROUGH MS 20046
MS 20073
MS 20074
AN 509 NK9
MS 24694
AN 525 NK525
MS 27039
NUTS
Steel Tension Steel Shear
AN 310 AN 320
AN 315 AN 364
AN 363 NAS 1022
AN 365 MS 17826
NAS 1021 MS 20364
MS 17825
MS 21045
MS 20365
MS 20500
NAS 679
Nut-bolt Torque Limits Torque Limits
size in-lbs. in-lbs.
Min. Max. Min. Max.
8-32 12 15 7 9
10-24 20 25 12 15
1/4-20 40 50 25 30
5/16-18 80 90 48 55
3/8-16 160 185 95 110
7/16-14 235 255 140 155
1/2-13 400 480 240 290
9/16-12 500 700 300 420
5/8-11 700 900 420 540
3/4-10 1,150 1,600 700 950
7/8-9 2,200 3,000 1,300 1,800
1-8 3,700 5,000 2,200 3,000
1-1/8-8 5,500 6,500 3,300 4,000
1-1/4-8 6,500 8,000 4,000 5,000