Sampling inspection

or at the lowest most point of the downward

(a) F i r s t p r o d u c t i o n i n s p e c t i o n . T h e f i r s t

s t r o k e . This enables the inspection of the longest

t e n engines when completed, and after successful

portion of cylinder bore affected by piston travel.

performance of the overhaul engine test

To achieve this, the flywheel must be rotated

schedule, shall have all cylinders, of each engine,

using splined wrench - 5120-793-7895 (fig. 4-

inspected by borescope. If no evidence of

51) allowing two pistons on each bank of

scuffing is detected, the sampling inspection

cylinders to be in the down position and enabling

method may be applied.

t h e complete inspection of an engine with only

(b) S a m p l i n g i n s p e c t i o n . U n d e r t h i s

t h r e e turns of the flywheel. The combinations of

method, after successful performance of the

overhaul engine test schedule, sample engines

cylinders that can be inspected at one time are as

f o l l o w s : (a) Nos. 2 and 5 right bank, - 3 and 4

s h a l l be selected for borescope inspection at the

left bank, (b) Nos. 3 and 4 right bank, - 1 and 6

rate of one in every 25 engines or one per month

when monthly production is less than 25. If

left bank, (c) Nos. 1 and 6 right bank and 2 and

scuffing of cylinder walls is detected, the five

5 left bank. To determine when the pistons to be

engines produced preceding the sample engine

c h e c k e d are at the lowest point of the downward

and the five engines produced after the sample

stroke, use a brass rod as a gage and insert it

through the fuel injector nozzle opening in the

e n g i n e will have all cylinders borescoped. Should

t h e r e be evidence of scuffing as a result of this

cylinder head (fig. 8-5). When piston stroke is in

i n s p e c t i o n , the inspector shall refuse acceptance

t h e maximum down position, mark the gage rod

of these engines and subsequent production

at the point where the rod protrudes from the

engines, until required corrections have been

c y l i n d e r head nozzle opening. This will facilitate

made and evidence to this effect has been

t h e proper positioning of the following cylinders

to be checked.

presented to inspector.

( 2 ) Refer to figures 4-126 through 4-141 to

remove upper cover shroud plates. Remove as

N o t e . Do not use borescope as a probe or gage

many fuel injection pump fuel tube support

in determining position of the piston in the

clamps as are accessible with the cover plates

c y l i n d e r s . The instrument can easily be damaged

removed. Disconnect fuel injector fuel return

when engine flywheel is rotated to position

hoses or tubes and fuel injection pump fuel tubes

pistons for borescoping.

from injector nozzles (fig. 4-150) using extreme

caution not to bend or kink the fuel tubes.

( 5 ) During inspection of the cylinders, it is

recommended that a record be made of each

(3) Loosen the fuel injector nozzles using

o p e n end fixed wrench - 5120-871-7198 (fig. 4-

cylinder checked and the position o f a n y

152). Remove fuel injector nozzle and holder

discrepancies noted. Relative position of a

assemblies from the 12 cylinder heads (fig. 4-

cylinder defect can be determined as though

153). To facilitate removal of No. 6L nozzle and

reading a clock with the top of the cylinder in the

h o l d e r assembly, remove the connector from the

1 2 : 0 0 position. A wear pattern beginning at the

nozzle head. This will allow the necessary

top of the cylinder and extending on a 30 degree

clearance with the shrouding to remove the

angle clockwise , would be recorded as a wear

nozzle and holder.

pattern extending from the 12:00 to 1:00

position.

(4) The relative position of the piston for

b o r e s c o p i n g the cylinders is in the down position

8-8