A lancair 4 in climb at 7000 ft diverted due to stabilizer trim runaway nose-up. Caused by incorrect...

Attributes
ACN	528659
Time
Date	200111
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sdl.airport
State Reference	AZ
Altitude	msl single value : 7000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sdl.tracon
Operator	general aviation : personal
Make Model Name	Amateur (Home) Built
Operating Under FAR Part	Part 91
Flight Phase	climbout : takeoff
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : private pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 16 flight time total : 1235 flight time type : 188
ASRS Report	528659
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other other : person 1
Resolutory Action	flight crew : overcame equipment problem flight crew : diverted to another airport
Consequence	other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft

Narrative:

Upon climb, electric trim malfunction caused the trim to rapidly move to a full pitch up status. Significant forward pressure was necessary. Assigned altitudes and vectors were difficult to maintain. Pilot was on phx departure when the problem was announced and a request for return to sdl was made. Pilot was able to successfully land the aircraft at sdl without incident. The mechanical problem has been evaluated and appears to be a malfunction of the interface between the electric trim and autoplt. Modification to the system is being made to prevent a repeat scenario. All preflight and preflight checklist items were observed. This experience has caused pilot to review autoplt and trim electrical system. Callback conversation with reporter revealed the following information: the reporter stated the airplane was a homebuilt kit lancair iv. The reporter said the stabilizer trim is operated by a single motor servo that is operated by the autoplt and the manual trim. The reporter stated the cause of the runaway trim was the wiring between the interface of the autoplt and the manual trim control. The reporter said the wiring has been replaced separating and isolating the control functions. The reporter stated this airplane had been flown for several yrs without experiencing this problem.

Original NASA ASRS Text

Title: A LANCAIR 4 IN CLB AT 7000 FT DIVERTED DUE TO STABILIZER TRIM RUNAWAY NOSE-UP. CAUSED BY INCORRECT WIRING BTWN THE AUTOPLT AND THE MANUAL TRIM SYS WIRING.

Narrative: UPON CLB, ELECTRIC TRIM MALFUNCTION CAUSED THE TRIM TO RAPIDLY MOVE TO A FULL PITCH UP STATUS. SIGNIFICANT FORWARD PRESSURE WAS NECESSARY. ASSIGNED ALTS AND VECTORS WERE DIFFICULT TO MAINTAIN. PLT WAS ON PHX DEP WHEN THE PROB WAS ANNOUNCED AND A REQUEST FOR RETURN TO SDL WAS MADE. PLT WAS ABLE TO SUCCESSFULLY LAND THE ACFT AT SDL WITHOUT INCIDENT. THE MECHANICAL PROB HAS BEEN EVALUATED AND APPEARS TO BE A MALFUNCTION OF THE INTERFACE BTWN THE ELECTRIC TRIM AND AUTOPLT. MODIFICATION TO THE SYS IS BEING MADE TO PREVENT A REPEAT SCENARIO. ALL PREFLT AND PREFLT CHKLIST ITEMS WERE OBSERVED. THIS EXPERIENCE HAS CAUSED PLT TO REVIEW AUTOPLT AND TRIM ELECTRICAL SYS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE AIRPLANE WAS A HOMEBUILT KIT LANCAIR IV. THE RPTR SAID THE STABILIZER TRIM IS OPERATED BY A SINGLE MOTOR SERVO THAT IS OPERATED BY THE AUTOPLT AND THE MANUAL TRIM. THE RPTR STATED THE CAUSE OF THE RUNAWAY TRIM WAS THE WIRING BTWN THE INTERFACE OF THE AUTOPLT AND THE MANUAL TRIM CTL. THE RPTR SAID THE WIRING HAS BEEN REPLACED SEPARATING AND ISOLATING THE CTL FUNCTIONS. THE RPTR STATED THIS AIRPLANE HAD BEEN FLOWN FOR SEVERAL YRS WITHOUT EXPERIENCING THIS PROB.

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.

A lancair 4 in climb at 7000 ft diverted due to stabilizer trim runaway nose-up. Caused by incorrect wiring between the autoplt and the manual trim system wiring.