Captain of an small transport executive jet momentarily lost control of the aircraft when the autopl...

Attributes
ACN	426290
Time
Date	199901
Day	Fri
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zob
State Reference	OH
Altitude	msl bound lower : 29000 msl bound upper : 29700
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other descent other
Route In Use	enroute airway : zob
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Experience	flight time last 90 days : 70 flight time total : 11000 flight time type : 1300
ASRS Report	426290
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude
Independent Detector	aircraft equipment other aircraft equipment : unspecified other controllera other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : overcame equipment problem
Consequence	faa : reviewed incident with flight crew Other
Supplementary
Air Traffic Incident	Pilot Deviation other

Narrative:

On the autoplt at FL410 we were cleared down to FL350. The descent was started on the autoplt. ZID called back and said I could maintain FL410. The controller thought we were landing in ohio, then realized our destination was in pennsylvania. We were at FL405 at that time so I used the control wheel to reverse the descent and climb back to FL410. Upon reaching FL410, the autoplt was chasing the altitude and not smooth like before the descent. I was hand flying to keep things smooth. ZOB started us down a little later. FL350, FL330, and then FL290 and please expedite. We were coming down at about 3000 FPM. Center asked if I could be level in 70 seconds. I replied that it would be no problem. I called level as requested and put the autoplt on with altitude hold. I noticed nothing unusual and was adding power for normal cruise. The aircraft pitched up sharply and the flight director was commanding 10 degrees up. I used the autoplt pitch trim wheel to command down pitch. The pitch continued up in spite of my down command. I then thought I had runaway pitch trim. I hit the disconnect (trim and autoplt), rolled the aircraft to 30-35 degrees bank as I pushed the nose down. Still trying not to disturb the passenger. The deviation was immediate (almost 700 ft high) and the correction was fast back to FL290. ATC and I talked about what had happened and I was given a phone number to call. During further flight and dscnts, I tried the autoplt and it tried to go to 10 degrees pitch up. During these attempts, I was aware of the problem and did not let it get away. After landing, the autoplt would not test properly. After further investigation and ctring of the autoplt pitch control wheel, the autoplt tested ok. On test flight next day all seemed ok. Avionics will check it out. I called ZOB as requested and the number never answered. I then called FSS and got another number which did answer and after talking to a couple of different people, I was told to call another number monday morning.

Original NASA ASRS Text

Title: CAPT OF AN SMT EXECUTIVE JET MOMENTARILY LOST CTL OF THE ACFT WHEN THE AUTOPLT PITCHED THE NOSE UP IN A CLB. THE RPTR DISCONNECTED THE AUTOPLT AND PITCH TRIM AND ROLLED THE ACFT FOR A NOSE DOWN POS IN ORDER TO GET BACK TO ASSIGNED ALT. ATC NOTICED THE ALT EXCURSION.

Narrative: ON THE AUTOPLT AT FL410 WE WERE CLRED DOWN TO FL350. THE DSCNT WAS STARTED ON THE AUTOPLT. ZID CALLED BACK AND SAID I COULD MAINTAIN FL410. THE CTLR THOUGHT WE WERE LNDG IN OHIO, THEN REALIZED OUR DEST WAS IN PENNSYLVANIA. WE WERE AT FL405 AT THAT TIME SO I USED THE CTL WHEEL TO REVERSE THE DSCNT AND CLB BACK TO FL410. UPON REACHING FL410, THE AUTOPLT WAS CHASING THE ALT AND NOT SMOOTH LIKE BEFORE THE DSCNT. I WAS HAND FLYING TO KEEP THINGS SMOOTH. ZOB STARTED US DOWN A LITTLE LATER. FL350, FL330, AND THEN FL290 AND PLEASE EXPEDITE. WE WERE COMING DOWN AT ABOUT 3000 FPM. CTR ASKED IF I COULD BE LEVEL IN 70 SECONDS. I REPLIED THAT IT WOULD BE NO PROB. I CALLED LEVEL AS REQUESTED AND PUT THE AUTOPLT ON WITH ALT HOLD. I NOTICED NOTHING UNUSUAL AND WAS ADDING PWR FOR NORMAL CRUISE. THE ACFT PITCHED UP SHARPLY AND THE FLT DIRECTOR WAS COMMANDING 10 DEGS UP. I USED THE AUTOPLT PITCH TRIM WHEEL TO COMMAND DOWN PITCH. THE PITCH CONTINUED UP IN SPITE OF MY DOWN COMMAND. I THEN THOUGHT I HAD RUNAWAY PITCH TRIM. I HIT THE DISCONNECT (TRIM AND AUTOPLT), ROLLED THE ACFT TO 30-35 DEGS BANK AS I PUSHED THE NOSE DOWN. STILL TRYING NOT TO DISTURB THE PAX. THE DEV WAS IMMEDIATE (ALMOST 700 FT HIGH) AND THE CORRECTION WAS FAST BACK TO FL290. ATC AND I TALKED ABOUT WHAT HAD HAPPENED AND I WAS GIVEN A PHONE NUMBER TO CALL. DURING FURTHER FLT AND DSCNTS, I TRIED THE AUTOPLT AND IT TRIED TO GO TO 10 DEGS PITCH UP. DURING THESE ATTEMPTS, I WAS AWARE OF THE PROB AND DID NOT LET IT GET AWAY. AFTER LNDG, THE AUTOPLT WOULD NOT TEST PROPERLY. AFTER FURTHER INVESTIGATION AND CTRING OF THE AUTOPLT PITCH CTL WHEEL, THE AUTOPLT TESTED OK. ON TEST FLT NEXT DAY ALL SEEMED OK. AVIONICS WILL CHK IT OUT. I CALLED ZOB AS REQUESTED AND THE NUMBER NEVER ANSWERED. I THEN CALLED FSS AND GOT ANOTHER NUMBER WHICH DID ANSWER AND AFTER TALKING TO A COUPLE OF DIFFERENT PEOPLE, I WAS TOLD TO CALL ANOTHER NUMBER MONDAY MORNING.

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.