 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
An hs-125 flight crew encountered moderate to severe airframe vibration while in cruise at FL400. The vibration ceased following a descent and disconnecting the autopilot; subsequently diverting to a nearby airport.
| Attributes | |
| ACN | 988543 |
| Time | |
| Date | 201201 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | BAe 125 Series 800 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Cruise |
| Route In Use | Direct |
| Flight Plan | IFR |
| Person 1 | |
| Function | Pilot Not Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 20 Flight Crew Total 11876 Flight Crew Type 35 |
| Events | |
| Anomaly | Inflight Event / Encounter Other / Unknown |
Narrative:
Cruising in occasional light chop at FL400 at mach .74 = 220 KIAS. The airframe started to vibrate at a rate similar to moderate to severe chop. We thought we had an airframe flutter or automated flight control system malfunction. We requested a lower altitude and were cleared to FL350. In the descent we declared an emergency. The captain used the autopilot to descend and level off at FL350 where he turned off the autopilot. The aircraft stopped vibrating. The captain flew the rest of the flight by hand. We asked center for a clearance to a nearby airport. They cleared us to the airport. In the descent we experienced some turbulence; but no more airframe vibration. We told center fuel and souls on board; and that the aircraft was under control and we no longer considered it to be an emergency. We landed uneventfully. The passengers said the wing tips fluctuated up and down about 3 ft at a rate of about 3 oscillations per second. This lasted for about 3 to 4 minutes.
Original NASA ASRS Text
Title: An HS-125 flight crew encountered moderate to severe airframe vibration while in cruise at FL400. The vibration ceased following a descent and disconnecting the autopilot; subsequently diverting to a nearby airport.
Narrative: Cruising in occasional light chop at FL400 at Mach .74 = 220 KIAS. The airframe started to vibrate at a rate similar to moderate to severe chop. We thought we had an airframe flutter or automated flight control system malfunction. We requested a lower altitude and were cleared to FL350. In the descent we declared an emergency. The Captain used the autopilot to descend and level off at FL350 where he turned off the autopilot. The aircraft stopped vibrating. The Captain flew the rest of the flight by hand. We asked Center for a clearance to a nearby airport. They cleared us to the airport. In the descent we experienced some turbulence; but no more airframe vibration. We told Center fuel and souls on board; and that the aircraft was under control and we no longer considered it to be an emergency. We landed uneventfully. The passengers said the wing tips fluctuated up and down about 3 FT at a rate of about 3 oscillations per second. This lasted for about 3 to 4 minutes.
Data retrieved from NASA's ASRS site as of July 2013 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.