ASN Wikibase Occurrence # 356500
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| Date: | Thursday 7 November 1996 |
| Time: | 21:15 LT |
| Type: |  McDonnell Douglas MD-11 |
| Owner/operator: | Delta Air Lines |
| Registration: | N814DE |
| MSN: | 48623/605 |
| Total airframe hrs: | 550 hours |
| Engine model: | P&W PW 4460 |
| Fatalities: | Fatalities: 0 / Occupants: 209 |
| Aircraft damage: | None |
| Category: | Serious incident |
| Location: | Dayton, OH -
 United States of America
|
| Phase: | En route |
| Nature: | Unknown |
| Departure airport: | GATWICK (KLGW) |
| Cincinnati, OH (KCVG) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
While en route the flight crew experienced a failure of the pitch trim control system. The crew was unable to change the pitch trim by the yoke mounted trim switches or the center console mounted horizontal stabilizer control handles. The crew stated that when the slats were extended on descent, they were unable to change stabilizer trim. Subsequent examination of the horizontal stabilizer pitch trim system found that there was no lubrication on the screw actuator assemblies and that the fuse pin had sheared in the output drive unit of the horizontal stabilizer drive gearbox. The sheared fuse pin locked the horizontal stabilizer in its last set position, as designed. A review of Assembly Orders at Douglas Aircraft (DAC) found that DAC production personnel and DAC Inspection personnel stamped the assembly orders indicating completion and acceptance of the lubrication. However, the investigation revealed that no lubrication had been applied to the screw actuator nuts.
Probable Cause: Failure of the output drive unit shear pin due to lack of lubrication to the screw actuator assemblies. Contributing to the cause was the aircraft manufacturer's production and inspection personnel failing to lubricate the screw assemblies after initial installation and again after washing.
Accident investigation:
 |
|
Sources:
NTSB IAD97IA018
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Mar-2024 07:53 | ASN Update Bot | Added |
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