A B737-300, on gear retraction after takeoff at 2000 ft, declared an emergency due to the nose gear falling out with a green light indication caused by a failed uplock mechanism.

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Attributes
ACN	483948
Time
Date	200008
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : pit.airport
State Reference	PA
Altitude	msl single value : 2000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : pit.tracon
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	climbout : initial
Route In Use	departure : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 15000 flight time type : 8000
ASRS Report	483948
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : nose landing gear pos. ind. other flight crewa other flight crewb
Resolutory Action	controller : issued alert flight crew : diverted to another airport
Consequence	other other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft Environmental Factor
Primary Problem	Aircraft

Narrative:

Flight departed normally and after placing gear handle to the off position, the nose gear came back out. As per company recommendation, the control of aircraft was handed over to first officer so the captain could coordinate with company and advise flight attendants and passenger. While captain was off the frequency, the first officer was receiving vector and altitude instructions from ATC. The first officer misheard an altitude assignment and read back the wrong altitude. ATC did not catch the mistake. Aircraft descended to 2000 ft MSL. ATC then issued a low altitude alert and the aircraft climbed back to 3000 ft MSL. Autoplt was used the entire time and WX was VMC. Controller should pay more attention to readbacks and even more attention to aircraft with problems. Callback conversation with reporter revealed the following information: the reporter stated maintenance took the airplane OTS and reported finding a bent rod or rods on the uplock mechanism. The reporter said the bent component was definitely on the uplock mechanism.

Original NASA ASRS Text

Title: A B737-300, ON GEAR RETRACTION AFTER TKOF AT 2000 FT, DECLARED AN EMER DUE TO THE NOSE GEAR FALLING OUT WITH A GREEN LIGHT INDICATION CAUSED BY A FAILED UPLOCK MECHANISM.

Narrative: FLT DEPARTED NORMALLY AND AFTER PLACING GEAR HANDLE TO THE OFF POS, THE NOSE GEAR CAME BACK OUT. AS PER COMPANY RECOMMENDATION, THE CTL OF ACFT WAS HANDED OVER TO FO SO THE CAPT COULD COORDINATE WITH COMPANY AND ADVISE FLT ATTENDANTS AND PAX. WHILE CAPT WAS OFF THE FREQ, THE FO WAS RECEIVING VECTOR AND ALT INSTRUCTIONS FROM ATC. THE FO MISHEARD AN ALT ASSIGNMENT AND READ BACK THE WRONG ALT. ATC DID NOT CATCH THE MISTAKE. ACFT DSNDED TO 2000 FT MSL. ATC THEN ISSUED A LOW ALT ALERT AND THE ACFT CLBED BACK TO 3000 FT MSL. AUTOPLT WAS USED THE ENTIRE TIME AND WX WAS VMC. CTLR SHOULD PAY MORE ATTN TO READBACKS AND EVEN MORE ATTN TO ACFT WITH PROBS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED MAINT TOOK THE AIRPLANE OTS AND RPTED FINDING A BENT ROD OR RODS ON THE UPLOCK MECHANISM. THE RPTR SAID THE BENT COMPONENT WAS DEFINITELY ON THE UPLOCK MECHANISM.

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.