ENGINE SMOKES (BLUE SMOKE) DURING OPERATION ONLY.

TM 9-2835-255-34

3-2. TROUBLESHOOTING - CONTINUED

E S - 2 2 . E N G I N E SMOKES (BLUE

(6)

d. ENGINE - CONTINUED

SMOKE) DURING OPERATION ONLY.

OK DURING START AND SHUTDOWN.

This section contains troubleshooting to locate and correct the cause(s)

of blue smoke from the exhaust during operation only, and not during

start or shutdown. Blue smoke is an indication of 0il leakage past seals

in oil-wetted areas into the exhaust path of the engine. This symptom is

usually accompanied by excessive oil consumption. There are many

potential causes of oil leakage throughout the engine. It is important

to carefully inspect the engine externally before disassembly to note

evidence of internal oil leakage. This evidence may assist in fault

isolating the problem to a module or component. If the oil reservoir is

o v e r f i l l e d , accessory gearbox (AGB) vent hose blocked, or oil pump

scavenging elements are damaged, oil scavenge pressures from the bearing

packages will increase and flooding of the bearing packages will cause

oil leakage past the seals. In addition to evidence noted during the

external visual inspection, engine disassembly may be required to

further fault isolate the condition. The art on the following pages

provides an overview of the AGB, lubrication and exhaust systems and

related components. Refer to these pages along with in-text art while

performing troubleshooting.

3-183

Change 5