Light twin jet lands with nose gear not centered causing aircraft to swerve and leave runway.

Attributes
ACN	258884
Time
Date	199312
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : phl
State Reference	PA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	common carrier : air taxi
Make Model Name	Small Transport, Low Wing, 2 Turbojet Eng
Flight Phase	landing other
Flight Plan	IFR
Person 1
Affiliation	company : air taxi
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : cfi
Experience	flight time last 90 days : 300 flight time total : 7800 flight time type : 5000
ASRS Report	258884
Person 2
Affiliation	company : air taxi
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : critical other anomaly other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : regained aircraft control
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

After departing bwi a nose gear unsafe or transient light remained illuminated. After cycling gear twice, light still remained illuminated. After touchdown in phl runway 35 I lowered nose slowly to the runway. At 85 KTS nosewheel touched. The aircraft turned abruptly 15 degrees left. With heavy right braking, the centerline of the runway could not be maintained and at 10 ft left of center I called for the drag chute which stopped the turn and straightened the course of the aircraft. We rolled off the runway into the grass and back onto the runway using nosewheel steering at low speed. No damage occurred to any runway lights or the aircraft and tower was not aware of the situation. The probable cause of red unsafe light was not enough N2 pressure to extend the strut and the centering pin did not engage in the safety cam centering nosewheel upon retraction. This was also the probable cause for the malfunction of the centering cam upon gear extension. Maintenance found some rolled seals which allowed fluid and N2 leakage. N2 pressure required to operate centering mechanisms.

Original NASA ASRS Text

Title: LIGHT TWIN JET LANDS WITH NOSE GEAR NOT CENTERED CAUSING ACFT TO SWERVE AND LEAVE RWY.

Narrative: AFTER DEPARTING BWI A NOSE GEAR UNSAFE OR TRANSIENT LIGHT REMAINED ILLUMINATED. AFTER CYCLING GEAR TWICE, LIGHT STILL REMAINED ILLUMINATED. AFTER TOUCHDOWN IN PHL RWY 35 I LOWERED NOSE SLOWLY TO THE RWY. AT 85 KTS NOSEWHEEL TOUCHED. THE ACFT TURNED ABRUPTLY 15 DEGS L. WITH HVY R BRAKING, THE CTRLINE OF THE RWY COULD NOT BE MAINTAINED AND AT 10 FT L OF CTR I CALLED FOR THE DRAG CHUTE WHICH STOPPED THE TURN AND STRAIGHTENED THE COURSE OF THE ACFT. WE ROLLED OFF THE RWY INTO THE GRASS AND BACK ONTO THE RWY USING NOSEWHEEL STEERING AT LOW SPD. NO DAMAGE OCCURRED TO ANY RWY LIGHTS OR THE ACFT AND TWR WAS NOT AWARE OF THE SIT. THE PROBABLE CAUSE OF RED UNSAFE LIGHT WAS NOT ENOUGH N2 PRESSURE TO EXTEND THE STRUT AND THE CENTERING PIN DID NOT ENGAGE IN THE SAFETY CAM CENTERING NOSEWHEEL UPON RETRACTION. THIS WAS ALSO THE PROBABLE CAUSE FOR THE MALFUNCTION OF THE CENTERING CAM UPON GEAR EXTENSION. MAINT FOUND SOME ROLLED SEALS WHICH ALLOWED FLUID AND N2 LEAKAGE. N2 PRESSURE REQUIRED TO OPERATE CENTERING MECHANISMS.

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.