ASN Wikibase Occurrence # 371302
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| Date: | Tuesday 5 April 1988 |
| Time: | 16:15 LT |
| Type: |  Beechcraft B90 |
| Owner/operator: | Critical Care Inc. |
| Registration: | N181LL |
| MSN: | LJ-440 |
| Total airframe hrs: | 5950 hours |
| Engine model: | P&W PT6A-135 |
| Fatalities: | Fatalities: 0 / Occupants: 5 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | St. Paul, MN -
 United States of America
|
| Phase: | En route |
| Nature: | Unknown |
| Departure airport: | Minot, ND (KMOT) |
| St. Paul, MN (KSTP) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
THE AIRPLANE WAS BEING OPERATED AS AN AIR AMBULANCE WHEN IT SUSTAINED SUBSTANTIAL DAMAGE DURING AN UNCOMMANDED HARD PITCHOVER. THE AIRPLANE WAS OPERATING IN VISUAL CONDITIONS ABOVE A SOLID CLOUD LAYER USING INSTRUMENT FLIGHT RULES. THE AIRPLANE RECOVERED FROM THE EXCURSION AND CONTINUED ON TO ITS DESTINATION. THE ATP RATED PILOT, THREE MEDICAL ATTENDANTS AND ONE PATIENT WERE NOT INJURED. TESTING OF THE PILOT'S WHEEL TRIM SWITCH SHOWED THE SWITCH WOULD STICK IN THE CLOSED OR ACTUATED POSITION AND NOT RETURN TO THE 'CENTER OFF' POSITION. THIS OCCURRED DURING TEMPERATURE CYCLING FROM ROOM TEMPERATURE TO BELOW FREEZING AND BACK AGAIN. THE CABIN HEATER HAD FAILED WITH AN OUTSIDE AIR TEMPERATURE OF -26 DEGS CELSIUS AND THE CABIN WAS COLD.
Probable Cause: MECHANICAL FAILURE AND STICKING OF THE PILOTS THUMB OPERATED TRIM SWITCH CAUSING NOSE DOWN PITCH COMMAND. THE FAILURE OF THE CABIN HEATER AND THE LOW CABIN TEMPERATURE ARE CONTRIBUTING FACTORS.
Accident investigation:
 |
|
Sources:
NTSB CHI88FA091
Location
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 25-Mar-2024 20:08 | ASN Update Bot | Added |
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