<< >> NASA ASRS Report 591016, August 2003

C310 pilot had an altitude deviation after disconnecting the autoplt, and finding the aircraft trimmed full nose up.

Attributes
ACN	591016
Time
Date	200308
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : zbw.artcc
State Reference	NH
Altitude	msl bound lower : 9000 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zbw.artcc
Operator	general aviation : personal
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	other
Function	oversight : pic
Qualification	pilot : multi engine pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 30 flight time total : 9600 flight time type : 500
ASRS Report	591016
Person 2
Affiliation	government : faa
Function	controller : radar
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude
Independent Detector	atc equipment other atc equipment : radar other controllera
Resolutory Action	controller : issued alert flight crew : returned to assigned altitude none taken : detected after the fact other
Consequence	other
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Assigned IFR altitude of 9000 ft on eastbound flight from pontiac (ptk) to portland (pwm). Uneventful flight until incident. In cruise noted slight fluctuation of horizon bar on just overhauled attitude indicator. Noted autoplt holding altitude within +/-100 ft, but electric elevator trim oscillating back and forth (with altitude hold apparently being accomplished with elevator inputs from autoplt). Decided to disengage autoplt. Upon disengagement aircraft pitched up unexpectedly to approximately 15 degrees nose up with resulting high climb rate. Large forward elevator force required to overcome up-trim. By the time back under control altitude noted was 9400 ft (probably higher before) center reported over 10000 ft on mode C. Autoplt re-engaged and performed normally. In future, need to anticipate an out-of-trim condition under such circumstances and need to assess position of elevator trim prior to autoplt disengage.

Related reports:

• UH60 flight crew experienced two altitude excursions after d...
• Altitude deviation altitude overshot in descent altitude cro...
• A CL65 first officer experiences an altitude deviation when ...

	Enter your search terms Submit search form
	Web www.37000feet.com

Original NASA ASRS Text

Title: C310 PLT HAD AN ALTDEV AFTER DISCONNECTING THE AUTOPLT, AND FINDING THE ACFT TRIMMED FULL NOSE UP.

Narrative: ASSIGNED IFR ALT OF 9000 FT ON EBOUND FLT FROM PONTIAC (PTK) TO PORTLAND (PWM). UNEVENTFUL FLT UNTIL INCIDENT. IN CRUISE NOTED SLIGHT FLUCTUATION OF HORIZON BAR ON JUST OVERHAULED ATTITUDE INDICATOR. NOTED AUTOPLT HOLDING ALT WITHIN +/-100 FT, BUT ELECTRIC ELEVATOR TRIM OSCILLATING BACK AND FORTH (WITH ALT HOLD APPARENTLY BEING ACCOMPLISHED WITH ELEVATOR INPUTS FROM AUTOPLT). DECIDED TO DISENGAGE AUTOPLT. UPON DISENGAGEMENT ACFT PITCHED UP UNEXPECTEDLY TO APPROX 15 DEGS NOSE UP WITH RESULTING HIGH CLB RATE. LARGE FORWARD ELEVATOR FORCE REQUIRED TO OVERCOME UP-TRIM. BY THE TIME BACK UNDER CTL ALT NOTED WAS 9400 FT (PROBABLY HIGHER BEFORE) CTR RPTED OVER 10000 FT ON MODE C. AUTOPLT RE-ENGAGED AND PERFORMED NORMALLY. IN FUTURE, NEED TO ANTICIPATE AN OUT-OF-TRIM CONDITION UNDER SUCH CIRCUMSTANCES AND NEED TO ASSESS POS OF ELEVATOR TRIM PRIOR TO AUTOPLT DISENGAGE.

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.