- Date
- April 5, 1988, 15:15 local (20:15 UTC)
- Place
- St. Paul, MN
- Injuries
- 5 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N181LLBeech B90
- Weather
- Instrument (IMC) · Day
- Status
- Completed · report June 25, 1990
- Report
- Approved by Office Director
- FAA report
- 19880405069699A
- Case key
- 13939
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
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.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
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.
Aircraft
- Registration
- N181LL
- Reported as
- Beech B90
- Category
- Airplane
- Serial number
- LJ-440
- Airframe hours
- 5,950
- Engine
- P&W PT6A-135, 550 horsepower, turbo prop
- Damage
- Substantial damage
- Flight
- Part 135
- Registered owner
- Critical Care Inc.
- Airworthiness certificate
- Standard, Normal
- Departed
- MOT · Minot, ND
- Destination
- STP · St. Paul, MN
- Flight plan
- IFR
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 41
- Certificate
- Airline transport
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 1, Valid Medical--no waivers/lim.
- Seat
- Left
- Flight hours
- 5,005 total · 900 in this make and model · 2,800 as pilot in command · 20 in the last 90 days
Weather
- Conditions
- Instrument (IMC) · Day
- Temperature
- 18 °F, dew point -0 °F
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.