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B727 crew had autoplt disengage with a 'stabilizer out of trim' warning light. Aircraft descended 400 ft below cleared altitude.
| Attributes | |
| ACN | 406327 |
| Time | |
| Date | 199806 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : iah |
| State Reference | TX |
| Altitude | msl bound lower : 3600 msl bound upper : 4000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : iah tower : ewr |
| Operator | common carrier : air carrier |
| Make Model Name | B727 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 250 flight time total : 14000 flight time type : 12000 |
| ASRS Report | 406327 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : commercial pilot : flight engineer pilot : instrument |
| Experience | controller military : 7 controller non radar : 3 controller radar : 3 flight time last 90 days : 210 flight time total : 16000 flight time type : 8800 |
| ASRS Report | 406630 |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We were assigned 4000 ft MSL while being vectored across final for runway 8 at houston intercontinental. Altitude hold was on. Autoplt did not trim pitch and 'stabilizer out of trim' light illuminated. Simultaneously the aircraft started descending. We descended 400 ft below assigned altitude before regaining control and climbing back to 4000 ft. Supplemental information from acn 406630: assigned to maintain 4000 ft MSL. We were being radar vectored to ILS runway 8, iah. Heavy rain and thunderstorm. Autoplt was on, altitude hold was on, autoplt 'stabilizer out of trim light' came on and aircraft pitched down 400 ft. Autoplt was disengaged and aircraft returned to 4000 ft. Rest of flight normal. Aircraft had a history of stabilizer out of trim malfunctions. During this incident our workload was very high. We were very near 'bingo' fuel and would have to proceed to our alternate if we did not get our approach clearance in approximately 2 mins. We were not in a published hold, but, we were being radar vectored in a holding pattern.
Original NASA ASRS Text
Title: B727 CREW HAD AUTOPLT DISENGAGE WITH A 'STABILIZER OUT OF TRIM' WARNING LIGHT. ACFT DSNDED 400 FT BELOW CLRED ALT.
Narrative: WE WERE ASSIGNED 4000 FT MSL WHILE BEING VECTORED ACROSS FINAL FOR RWY 8 AT HOUSTON INTERCONTINENTAL. ALT HOLD WAS ON. AUTOPLT DID NOT TRIM PITCH AND 'STABILIZER OUT OF TRIM' LIGHT ILLUMINATED. SIMULTANEOUSLY THE ACFT STARTED DSNDING. WE DSNDED 400 FT BELOW ASSIGNED ALT BEFORE REGAINING CTL AND CLBING BACK TO 4000 FT. SUPPLEMENTAL INFO FROM ACN 406630: ASSIGNED TO MAINTAIN 4000 FT MSL. WE WERE BEING RADAR VECTORED TO ILS RWY 8, IAH. HVY RAIN AND TSTM. AUTOPLT WAS ON, ALT HOLD WAS ON, AUTOPLT 'STABILIZER OUT OF TRIM LIGHT' CAME ON AND ACFT PITCHED DOWN 400 FT. AUTOPLT WAS DISENGAGED AND ACFT RETURNED TO 4000 FT. REST OF FLT NORMAL. ACFT HAD A HISTORY OF STABILIZER OUT OF TRIM MALFUNCTIONS. DURING THIS INCIDENT OUR WORKLOAD WAS VERY HIGH. WE WERE VERY NEAR 'BINGO' FUEL AND WOULD HAVE TO PROCEED TO OUR ALTERNATE IF WE DID NOT GET OUR APCH CLRNC IN APPROX 2 MINS. WE WERE NOT IN A PUBLISHED HOLD, BUT, WE WERE BEING RADAR VECTORED IN A HOLDING PATTERN.
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.