# NTSB DEN90LA047: Mitsubishi MU-2B-25, N99SR, Broomfield, CO, January 19, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: January 19, 1990, 15:44 local (22:44 UTC)
- Place: Broomfield, CO
- Coordinates: 39.939228, -105.059585 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.9392&lon=-105.0596&mi=10
- Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report September 29, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 17884
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN90LA047
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17884/pdf
- Page: https://openairdocs.org/ntsb/DEN90LA047

## Probable cause

LOSS OF DIRECTIONAL CONTROL BY THE PILOT, DURING TAKEOFF GROUND RUN. CONTRIBUTING TO THIS ACCIDENT WERE A LOSS OF POWER ON THE LEFT ENGINE DUE TO SNOW INGESTION, HEAVY SNOW SHOWERS IN PROGRESS AND AN ICY, SNOW COVERED RUNWAY.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of engine power, takeoff - roll/run
  - 1 engine
  - compressor assembly - blocked(partial) (contributing factor)
  - weather condition - snow (contributing factor)
  - weather condition - icing conditions (contributing factor)
  - weather condition - obscuration (contributing factor)
- Loss of control - on ground/water, takeoff - roll/run
  - terrain condition - icy
  - terrain condition - snow covered
  - directional control - not maintained, pilot in command (cause)
- On ground/water collision with object, takeoff - roll/run
  - object - sign
  - object - runway light

## Analysis

THE PILOT SAID THAT DURING TAKEOFF GROUND ROLL, THE LEFT ENGINE LOST RPM. THE PILOT LOST DIRECTIONAL CONTROL AND THE PLANE DEPARTED THE LEFT SIDE OF THE RUNWAY. THE PLANE STRUCK A RUNWAY SIGN AND 2 RUNWAY LIGHTS. IT THEN SKIDDED SIDEWAYS FOR 3000 FEET, CROSSED THE RUNWAY AND NOSED DOWN IN A DITCH. THERE WERE HEAVY SNOW SHOWERS IN PROGRESS AT THE TIME OF THE ACDNT AND THE RUNWAY WAS COVERED BY SNOW.

## Aircraft

- Registration: [N99SR](https://openairdocs.org/aircraft/N99SR), registered now, S/N 315, built 1974 (OpenAirDocs)
- Reported make and model: MITSUBISHI MU-2B-25
- Registry model: [Mitsubishi MU-2B-25](https://openairdocs.org/model/mitsubishi-mu-2b-25) (registry code 5780409) (OpenAirDocs)
- Registry engine: [AiResearch TPE331 series](https://openairdocs.org/engine/airesearch-tpe331-series) (registry code 01514, turbo-prop) (OpenAirDocs)
- Category: Airplane
- Serial number: 315
- Airframe hours: 1642
- Engines: GARRETT TPE-331 840 horsepower turbo prop
- Damage: Substantial damage
- Fire: On-Ground
- Flight: Business, Part 91
- Registered owner: Dewey H. Cosgrove
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, August 14, 1989, 80 hours before
- Departed: BJC
- Destination: CFW, CRESTVIEW, FL
- Flight plan: IFR
- Airport: BJC, Jefferson County, runway 29R, 9,000 × 100 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 55; airline transport, flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 20,963 total, 2,075 in this make and model, 14,239 as pilot in command, 66 in the last 90 days, 44 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Instrument (IMC), Day
- Wind: 350° at 9 knots
- Lowest ceiling: 200 ft
- Temperature: 23 °F, dew point 21 °F
- Altimeter: 29.00 inHg

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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