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".
(c) Select the desired test state to display 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.
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,
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.
lnsert a copy of this TB into the pilot's information file, and place a copy of
this TB in the aircraft logbook.
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.
For aircraft that pass the screening inspection, if the combustor turbine
section is removed and replaced for any reason while on the aircraft, the
Engines that pass the screening inspection that are removed and
re-installed for any reason must be re-installed IAW paragraph 8. of this
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: