SECTION I. HOW TO USE TROUBLESHOOTING

TM 9-2835-255-34

SECTION I. HOW TO USE TROUBLESHOOTING

SCOPE:

Troubleshooting is a step-by-step process for determining the cause of

an engine problem. This section will explain the overall approach to the

troubleshooting procedures presented in chapter 3. References within

this manual will be by page number. Some references to other manuals

will only be by TM number. I f y o u a r e g i v e n a r e f e r e n c e t o T M 2 0 - 1 , f o r

instance, r e f e r t o t h e -20 manual for your engine and go to the index at

the end of the last volume to find the proper task location. For further

information on references, be sure to read How to Use This Manual on

page iii.

PURPOSE:

There are

four

key

steps

needed

for

good

troubleshooting:

I d e n t i f y t h e S y m pt o m . T o i d e n t i f y t h e s y m p t o m , r e a d t h e D A F o r m

2404, 2407 or 5504 that was filled out and describes the engine

symptom. I f s y m p t o m i s o n e t h a t c a n b e v e r i f i e d , s u c h a s l o w

pressure compressor rubs when turned by hand, verify the

symptom.

Find the Procedure. Use the Fault Symptom Index (Section II) to

locate your symptom and the paragraph and page number of the

t r o u b l e s h o o t i n g p r o c e d u r e y o u n e e d . The symptom you have may not

be worded exactly as described in the index but find the symptom

that most closely resembles the engine malfunction.

Isolate the Fault. All troubleshooting procedures are located in

Troubleshooting (Section III). They are in the form of fault

isolation flow charts; see Sample Procedure on page 3-4. Each

flow chart begins with a specific fault symptom. Included at

the

beginning of most flow charts, is a brief description and

illustration of the system or parts you are troubleshooting for

that particular symptom. Refer to this to help you understand

the troubleshooting logic in the flow chart. Step-by-step

instructions for finding and correcting the fault are given for

each symptom. I l l u s t r a t i o n s a r e i n c l u d e d t o s h o w t h e l o c a t i o n o f

test points and engine related hardware. Carefully answer each

question in the flow chart.

Verify the Repair. Most fault isolation procedures will lead to

the replacement of a component. Follow the reference to the

maintenance procedure, a n d r e p l a c e t h e f a u l t y p a r t o r m o d u l e .

If your symptom was one that could be verified, such as low

pressure compressor rubs when turned by hand, make the repair,

and verify that the symptom is gone. The statement verify

p r o b l e m i s s o l v e d . " means to operate the engine to be sure Your

symptom or any related symptom is no longer present. If your

engine still has a problem after a troubleshooting procedure has

been performed, it may have had more than one fault. Check the

Fault Symptom Index for another troubleshooting procedure and

continue to troubleshoot.

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