A return land mandated when the flight crew of a B737 feel a vibration and a rumbling sound leveling...

Attributes
ACN	622220
Time
Date	200303
Day	Fri
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zhu.artcc
State Reference	TX
Altitude	msl single value : 23000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zhu.artcc
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 120 flight time total : 24000 flight time type : 8000
ASRS Report	622220
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Experience	flight time last 90 days : 120 flight time total : 10000 flight time type : 2500
ASRS Report	622221
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : diverted to another airport flight crew : landed as precaution other
Consequence	other other
Supplementary
Problem Areas	Maintenance Human Performance Environmental Factor Company Aircraft Weather
Primary Problem	Aircraft

Narrative:

During initial climb from iah, aircraft was leveled at FL230 (ATC instructions). The airspeed was 300 KIAS with all normal cockpit indications. Autoplt on. A sudden rumbling sound began with a pronounced vibration in the floor. It lasted 5 seconds, then stopped. Within seconds, it started again for approximately 5 seconds. With knowledge that the aircraft had been deiced the day before and washed the night before, 'elevator tab limit cycle oscillation' was suspected. The airspeed was immediately reduced below the limit for this condition. 260 KIAS was used. Dispatch/maintenance was called. The safest course of action at this point was returning to iah.

Original NASA ASRS Text

Title: A RETURN LAND MANDATED WHEN THE FLT CREW OF A B737 FEEL A VIBRATION AND A RUMBLING SOUND LEVELING OFF AT FL230.

Narrative: DURING INITIAL CLB FROM IAH, ACFT WAS LEVELED AT FL230 (ATC INSTRUCTIONS). THE AIRSPD WAS 300 KIAS WITH ALL NORMAL COCKPIT INDICATIONS. AUTOPLT ON. A SUDDEN RUMBLING SOUND BEGAN WITH A PRONOUNCED VIBRATION IN THE FLOOR. IT LASTED 5 SECONDS, THEN STOPPED. WITHIN SECONDS, IT STARTED AGAIN FOR APPROX 5 SECONDS. WITH KNOWLEDGE THAT THE ACFT HAD BEEN DEICED THE DAY BEFORE AND WASHED THE NIGHT BEFORE, 'ELEVATOR TAB LIMIT CYCLE OSCILLATION' WAS SUSPECTED. THE AIRSPD WAS IMMEDIATELY REDUCED BELOW THE LIMIT FOR THIS CONDITION. 260 KIAS WAS USED. DISPATCH/MAINT WAS CALLED. THE SAFEST COURSE OF ACTION AT THIS POINT WAS RETURNING TO IAH.

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.

A return land mandated when the flight crew of a B737 feel a vibration and a rumbling sound leveling off at FL230.