Air carrier widebody transport's nose gear collapses as 'nosewheel steering' switch is activated.

Attributes
ACN	239299
Time
Date	199304
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : str
State Reference	FO
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 3 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	ground : holding ground other : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 85 flight time total : 21000 flight time type : 1000
ASRS Report	239299
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 6900
ASRS Report	238842
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	none taken : unable
Consequence	other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

The last item on the before takeoff checklist 'rudder pedal steering switch -- on.' when switch was turned on, the nose gear retracted! Tower was notified -- fire equipment was sent but not used, passenger were deplaned through forward left loading door with use of airstairs. No one was hurt. Callback conversation with reporter revealed the following information: reporter indicated that the landing gear 'nose gear module' was found to be defective in post-flight inspection. The module is manufactured by an unknown company and was found to be leaking hydraulic fluid. An obvious connection between the turning on of the nosewheel steering switch and the activation of the down lock release because of the defective module. The air carrier used to place the part directly into service and they now bench check it first as this is the second incident of this nature.

Original NASA ASRS Text

Title: ACR WDB'S NOSE GEAR COLLAPSES AS 'NOSEWHEEL STEERING' SWITCH IS ACTIVATED.

Narrative: THE LAST ITEM ON THE BEFORE TKOF CHKLIST 'RUDDER PEDAL STEERING SWITCH -- ON.' WHEN SWITCH WAS TURNED ON, THE NOSE GEAR RETRACTED! TWR WAS NOTIFIED -- FIRE EQUIP WAS SENT BUT NOT USED, PAX WERE DEPLANED THROUGH FORWARD L LOADING DOOR WITH USE OF AIRSTAIRS. NO ONE WAS HURT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR INDICATED THAT THE LNDG GEAR 'NOSE GEAR MODULE' WAS FOUND TO BE DEFECTIVE IN POST-FLT INSPECTION. THE MODULE IS MANUFACTURED BY AN UNKNOWN COMPANY AND WAS FOUND TO BE LEAKING HYD FLUID. AN OBVIOUS CONNECTION BTWN THE TURNING ON OF THE NOSEWHEEL STEERING SWITCH AND THE ACTIVATION OF THE DOWN LOCK RELEASE BECAUSE OF THE DEFECTIVE MODULE. THE ACR USED TO PLACE THE PART DIRECTLY INTO SVC AND THEY NOW BENCH CHK IT FIRST AS THIS IS THE SECOND INCIDENT OF THIS NATURE.

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.