<< >> NASA ASRS Report 547903, May 2002

A B737-800 in cruise FL350 experienced elevator vibration. Airplane had been deiced prior to departure. Per ad speed restricted to 270 knots.

Attributes
ACN	547903
Time
Date	200205
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zme.artcc
Operator	common carrier : air carrier
Make Model Name	B737-800
Operating Under FAR Part	Part 121
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 17000 flight time type : 2200
ASRS Report	547903
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Experience	flight time last 90 days : 240 flight time total : 5500 flight time type : 2000
ASRS Report	547902
Events
Anomaly	aircraft equipment problem : critical maintenance problem : improper documentation maintenance problem : improper maintenance non adherence : far non adherence : published procedure
Independent Detector	other flight crewa other flight crewb
Resolutory Action	none taken : detected after the fact
Consequence	other other
Factors
Maintenance	contributing factor : schedule pressure performance deficiency : fault isolation performance deficiency : inspection performance deficiency : non compliance with legal requirements
Supplementary
Problem Areas	Aircraft Maintenance Human Performance
Primary Problem	Maintenance Human Performance

Narrative:

Deiced to remove visible frost. Complied with ad. Experienced elevator vibration during cruise. Contacted maintenance control and dispatch. Slowed airspeed. Vibrations ceased. Advised to continue to ZZZ. Landed normally. Understood elevator cleaning procedure would be done to comply with ad since ad was entered into logbook along with amended release. Due to discussion with maintenance control initial logbook write up reference vibration was not done due to ad write up which requires the elevator inspection. Met with maintenance personnel later to discuss further evaluation and input. Callback conversation with reporter revealed the following information: the reporter stated the maintenance department and he believed the elevator inspection could be deferred as long as the speed restriction was observed. The reporter said everyone was convinced the vibration was caused by the deicing and was related to the airworthiness directive, the reporter said the actual cause was an elevator tab bushing worn beyond limits.

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Original NASA ASRS Text

Title: A B737-800 IN CRUISE FL350 EXPERIENCED ELEVATOR VIBRATION. AIRPLANE HAD BEEN DEICED PRIOR TO DEP. PER AD SPEED RESTRICTED TO 270 KNOTS.

Narrative: DEICED TO REMOVE VISIBLE FROST. COMPLIED WITH AD. EXPERIENCED ELEVATOR VIBRATION DURING CRUISE. CONTACTED MAINT CTL AND DISPATCH. SLOWED AIRSPEED. VIBRATIONS CEASED. ADVISED TO CONTINUE TO ZZZ. LANDED NORMALLY. UNDERSTOOD ELEVATOR CLEANING PROCEDURE WOULD BE DONE TO COMPLY WITH AD SINCE AD WAS ENTERED INTO LOGBOOK ALONG WITH AMENDED RELEASE. DUE TO DISCUSSION WITH MAINT CTL INITIAL LOGBOOK WRITE UP REF VIBRATION WAS NOT DONE DUE TO AD WRITE UP WHICH REQUIRES THE ELEVATOR INSPECTION. MET WITH MAINT PERSONNEL LATER TO DISCUSS FURTHER EVALUATION AND INPUT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE MAINT DEPARTMENT AND HE BELIEVED THE ELEVATOR INSPECTION COULD BE DEFERRED AS LONG AS THE SPEED RESTRICTION WAS OBSERVED. THE RPTR SAID EVERYONE WAS CONVINCED THE VIBRATION WAS CAUSED BY THE DEICING AND WAS RELATED TO THE AIRWORTHINESS DIRECTIVE, THE RPTR SAID THE ACTUAL CAUSE WAS AN ELEVATOR TAB BUSHING WORN BEYOND LIMITS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.