Narrative:

At approximately XA20 on 07/xa/02, I received clearance to taxi onto runway 12 at abq airport to conduct a high speed taxi test of my C402B. Conditions were VFR, temperature approximately 70 degrees F with wind light and variable. Calculated aircraft weight was 6250 pounds with myself, an aviation mechanic and approximately 160 gallons of fuel on board. The test was to be a check of maintenance done to correct a severe nosewheel shake encountered during the takeoff roll of a flight attempted earlier that morning. The maintenance performed consisted of adjusting the nosewheel steering cables and servicing the steering dampener. Because the nosewheel shake had appeared at between 50-60 KTS, I planned to accelerate the aircraft to 70 KTS before shutting down in order to verify the condition was truly repaired. I decided to request a runway for the test to take advantage of its extra length and width in the event that problems were encountered. The airport was very busy at this time with landing and departing traffic using runway 3 and runway 8I chose 6000 ft X 150 ft runway 12 for the test after reviewing the accelerate/stop data contained in the aircraft poh and because I felt that airport operations would preclude my using a longer runway for the test. The published data showed a required distance of 4100 ft for our conditions. To this figure, I added 20% for 4920 ft required then rounded up to 5200 ft. I planned to begin my test from a point on runway 12 south of the ILS critical area for the active runway 8. Although this would shorten the length of the runway available for the test to approximately 5800 ft I felt satisfied that I had built sufficient cushion into my calculations to compensation for real world conditions, especially since I would be accelerating to just over 70 KTS and shutting down rather than to the 91 KT rotation speed used to derive the poh data. I advanced the throttles and accelerated the aircraft to 70 KTS. Acceleration appeared to be normal and was without vibration. Satisfied that the original problem condition had been repaired I reduced the throttles to idle at just over 70 KTS and began heavy braking. The aircraft tracked straight ahead, but did not appear to slow although the brake pedal pressure felt normal. Continued heavy braking resulted in only slow deceleration. With the available runway rapidly decreasing I decided against locking the brakes or using flaps in an effort to slow the aircraft as I felt that either of these actions would be ineffective and would result in a loss of control. In addition, because I had slowed to less than 50 KTS, advancing the throttles, attempting to accelerate to takeoff speed and taking off in the distance remaining was not an option. I chose instead to continue heavy braking and ride the aircraft onto the overrun area if we had not stopped upon reaching the end of the runway. The aircraft had slowed to approximately 20-25 KTS as it exited the runway onto the overrun area. Just prior to end of the runway, I reduced the mixtures to idle cutoff so that the engines would be shut down and hopefully sustain less damage should the nose gear collapse. The overrun area consisted of a flat, sandy area that descended from runway elevation about 1000 ft to the airport perimeter road. The aircraft tracked straight ahead and continued to slow as we proceeded down the hill. The nose of the aircraft began to porpoise due to the uneven nature of the ground with the nosewheel eventually digging into the sand and the strut folding back. Prior to the aircraft stopping, I turned off the fuel valves and switched off the magnetos and master switch. The aircraft came to rest without injury to persons on board or fire. The mechanic and I exited the aircraft and waited for emergency personnel to arrive.

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Original NASA ASRS Text

Title: A C402B CPR ACFT RUNS OFF THE END OF RWY 12 DURING A HIGH SPD TAXI TEST AND HAS THE NOSE GEAR COLLAPSE AS THE ACFT ENTERED THE OVERRUN AREA AT ABQ, NM.

Narrative: AT APPROX XA20 ON 07/XA/02, I RECEIVED CLRNC TO TAXI ONTO RWY 12 AT ABQ ARPT TO CONDUCT A HIGH SPD TAXI TEST OF MY C402B. CONDITIONS WERE VFR, TEMP APPROX 70 DEGS F WITH WIND LIGHT AND VARIABLE. CALCULATED ACFT WT WAS 6250 LBS WITH MYSELF, AN AVIATION MECH AND APPROX 160 GALLONS OF FUEL ON BOARD. THE TEST WAS TO BE A CHK OF MAINT DONE TO CORRECT A SEVERE NOSEWHEEL SHAKE ENCOUNTERED DURING THE TKOF ROLL OF A FLT ATTEMPTED EARLIER THAT MORNING. THE MAINT PERFORMED CONSISTED OF ADJUSTING THE NOSEWHEEL STEERING CABLES AND SVCING THE STEERING DAMPENER. BECAUSE THE NOSEWHEEL SHAKE HAD APPEARED AT BTWN 50-60 KTS, I PLANNED TO ACCELERATE THE ACFT TO 70 KTS BEFORE SHUTTING DOWN IN ORDER TO VERIFY THE CONDITION WAS TRULY REPAIRED. I DECIDED TO REQUEST A RWY FOR THE TEST TO TAKE ADVANTAGE OF ITS EXTRA LENGTH AND WIDTH IN THE EVENT THAT PROBS WERE ENCOUNTERED. THE ARPT WAS VERY BUSY AT THIS TIME WITH LNDG AND DEPARTING TFC USING RWY 3 AND RWY 8I CHOSE 6000 FT X 150 FT RWY 12 FOR THE TEST AFTER REVIEWING THE ACCELERATE/STOP DATA CONTAINED IN THE ACFT POH AND BECAUSE I FELT THAT ARPT OPS WOULD PRECLUDE MY USING A LONGER RWY FOR THE TEST. THE PUBLISHED DATA SHOWED A REQUIRED DISTANCE OF 4100 FT FOR OUR CONDITIONS. TO THIS FIGURE, I ADDED 20% FOR 4920 FT REQUIRED THEN ROUNDED UP TO 5200 FT. I PLANNED TO BEGIN MY TEST FROM A POINT ON RWY 12 S OF THE ILS CRITICAL AREA FOR THE ACTIVE RWY 8. ALTHOUGH THIS WOULD SHORTEN THE LENGTH OF THE RWY AVAILABLE FOR THE TEST TO APPROX 5800 FT I FELT SATISFIED THAT I HAD BUILT SUFFICIENT CUSHION INTO MY CALCULATIONS TO COMPENSATION FOR REAL WORLD CONDITIONS, ESPECIALLY SINCE I WOULD BE ACCELERATING TO JUST OVER 70 KTS AND SHUTTING DOWN RATHER THAN TO THE 91 KT ROTATION SPD USED TO DERIVE THE POH DATA. I ADVANCED THE THROTTLES AND ACCELERATED THE ACFT TO 70 KTS. ACCELERATION APPEARED TO BE NORMAL AND WAS WITHOUT VIBRATION. SATISFIED THAT THE ORIGINAL PROB CONDITION HAD BEEN REPAIRED I REDUCED THE THROTTLES TO IDLE AT JUST OVER 70 KTS AND BEGAN HVY BRAKING. THE ACFT TRACKED STRAIGHT AHEAD, BUT DID NOT APPEAR TO SLOW ALTHOUGH THE BRAKE PEDAL PRESSURE FELT NORMAL. CONTINUED HVY BRAKING RESULTED IN ONLY SLOW DECELERATION. WITH THE AVAILABLE RWY RAPIDLY DECREASING I DECIDED AGAINST LOCKING THE BRAKES OR USING FLAPS IN AN EFFORT TO SLOW THE ACFT AS I FELT THAT EITHER OF THESE ACTIONS WOULD BE INEFFECTIVE AND WOULD RESULT IN A LOSS OF CTL. IN ADDITION, BECAUSE I HAD SLOWED TO LESS THAN 50 KTS, ADVANCING THE THROTTLES, ATTEMPTING TO ACCELERATE TO TKOF SPD AND TAKING OFF IN THE DISTANCE REMAINING WAS NOT AN OPTION. I CHOSE INSTEAD TO CONTINUE HVY BRAKING AND RIDE THE ACFT ONTO THE OVERRUN AREA IF WE HAD NOT STOPPED UPON REACHING THE END OF THE RWY. THE ACFT HAD SLOWED TO APPROX 20-25 KTS AS IT EXITED THE RWY ONTO THE OVERRUN AREA. JUST PRIOR TO END OF THE RWY, I REDUCED THE MIXTURES TO IDLE CUTOFF SO THAT THE ENGS WOULD BE SHUT DOWN AND HOPEFULLY SUSTAIN LESS DAMAGE SHOULD THE NOSE GEAR COLLAPSE. THE OVERRUN AREA CONSISTED OF A FLAT, SANDY AREA THAT DSNDED FROM RWY ELEVATION ABOUT 1000 FT TO THE ARPT PERIMETER ROAD. THE ACFT TRACKED STRAIGHT AHEAD AND CONTINUED TO SLOW AS WE PROCEEDED DOWN THE HILL. THE NOSE OF THE ACFT BEGAN TO PORPOISE DUE TO THE UNEVEN NATURE OF THE GND WITH THE NOSEWHEEL EVENTUALLY DIGGING INTO THE SAND AND THE STRUT FOLDING BACK. PRIOR TO THE ACFT STOPPING, I TURNED OFF THE FUEL VALVES AND SWITCHED OFF THE MAGNETOS AND MASTER SWITCH. THE ACFT CAME TO REST WITHOUT INJURY TO PERSONS ON BOARD OR FIRE. THE MECH AND I EXITED THE ACFT AND WAITED FOR EMER PERSONNEL TO ARRIVE.

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.