Review data

TB 1-2840-229-20-17

i. Review data

(1) To display the spectral data, perform the following:

(a) With the desired flight ID selected, enter the display mode by pressing "F2".

(b) Select "ONE TEST STATE" and press "DO".

(d) Press "DO" again at "FWD LIFTING EYE" to view data.

(2) This will display the vibration spectrum. Use the cursor keys to move the reference line to

view vibration peaks between 3600 Hz and 3950 Hz.

CAUTION

No parts are to be removed from engines that failed the AVA Vibration

inspection except quick change assembly (QCA) items.

9. Correction Procedures.

a. For aircraft released for flight, as part of the pre-mission briefing, the pilot in command shall review

the symptoms concerning this possible N2 failure mode, and the emergency actions of TM 55-1520-236-10,

paragraph 9-18., Emergency Procedure for Engine Overspeed.

NOTE

Units with aircraft that fail the screening inspection may replace the engine.

However, the status symbol of the aircraft shall not change until the

screening procedure is repeated with the newly installed engine. If a new

engine is installed, the inspection requirements of this TB must be

completed prior to the in-flight requirements of TM 55-2840-229-23.

NOTE

lnsert a copy of this TB into the pilot's information file, and place a copy of

this TB in the aircraft logbook.

NOTE

Recovery from N2 spur gear failure training video tape will be distributed by

the AH-1 PM the week of 24 June 98 to each installation/activity/facility

operating AH-1 aircraft.

b. Aircraft that fail the initial (or any subsequent 25-hour) vibration screening inspection shall be

assigned the condition symbol of Red X. Further information/guidance will be in a follow-on

SOF message/TB concerning a long-term corrective action, which will clear the Red X.

NOTE

For aircraft that pass the screening inspection, if the combustor turbine

section is removed and replaced for any reason while on the aircraft, the

inspection of paragraph 8. shall be repeated.

NOTE

Engines that pass the screening inspection that are removed and

re-installed for any reason must be re-installed IAW paragraph 8. of this

TB.

c. Any aircraft which passes the initial vibration screening is cleared for flight. As part of their

operational risk management process, commanders at all levels with aircraft that have passed the screening

should consider the following risk mitigators: