# NTSB ATL86LA236: Enstrom F-28C, N549H, Coshocton, OH, September 1, 1986

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: September 1, 1986, 11:50 local (15:50 UTC)
- Place: Coshocton, OH
- Coordinates: 40.260253, -81.840026 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.2603&lon=-81.8400&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 3 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 7175
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL86LA236
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/7175/pdf
- Page: https://openairdocs.org/ntsb/ATL86LA236

## Sequence of events

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

- Miscellaneous/other, takeoff - initial climb
  - planning/decision - improper, pilot in command (cause)
  - terrain condition - high obstruction(s) (contributing factor)
  - collective - excessive, pilot in command (cause)
  - throttle/power control - improper use of, pilot in command (cause)
  - aircraft performance,climb capability - other
  - rotor rpm - not maintained, pilot in command (cause)
- In flight collision with terrain/water, takeoff

## Analysis

THE PLT INITIATED A MAXIMUM POWER TAKEOFF FROM A CONFINED PARKING LOT WITH 2 PASSENGERS ON BOARD. THE AREA WAS BOARDERED BY OBSTRUCTIONS & PEOPLE. THE PLT RPRTD THAT DURING LIFT-OFF, SHE INCREASED POWER TO 2900 RPM, LIFTED OFF TO A 4' HOVER WITH 33' OF MANIFOLD PRESSURE, THEN BEGAN A MAX PERFORMANCE TAKEOFF, 'PULLING POWER AND TURNING THROTTLE' FOR EXTRA RPM WITH SLOW FORWARD SPEED, REACHING 36' OF MANIFOLD PRESSURE. AT APRX 15' AGL, THE PLT NOTED A DECREASE IN RPM. SHE INCREASED THROTTLE APPLICATION, THEN DECREASED THE COLLECTIVE, BUT WAS UNABLE TO RECOVER THE LOSS OF RPM. SHE MADE A LEFT PEDAL TURN TO AVOID OBSTRUCTIONS & PEOPLE. SUBSEQUENTLY, THE HELICOPTER TOUCHED DOWN HARD & WAS DAMAGED. AN EXAM OF THE ENG DID NOT REVEAL ANY DEFECTS. THE FLT MANUAL WARNED THAT LOSS OF ROTOR & ENG RPM WOULD FOLLOW WHEN THE ENG WAS OVERBOOSTED. AT 36.5' OF MANIFOLD PRESSURE, THE POP-OFF VALVE WOULD HAVE ACTIVATED WHICH WOULD HAVE RESULTED IN A SLIGHT POWER LOSS.

## Aircraft

- Registration: [N549H](https://openairdocs.org/aircraft/N549H), registered now, S/N 345, built 1976 (OpenAirDocs)
- Reported make and model: ENSTROM F-28C
- Registry model: [Enstrom F-28C](https://openairdocs.org/model/enstrom-f-28c) (registry code 3300407) (OpenAirDocs)
- Category: Helicopter
- Serial number: 345
- Airframe hours: 1132
- Engines: LYCOMING HIO-360-E1AD 205 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Trans Rotor, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, April 11, 1986, 68 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 33; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 412 total, 388 in this make and model, 291 as pilot in command, 35 in the last 90 days, 7 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 150° at 9 knots
- Visibility: 7 statute miles
- Lowest ceiling: 1,700 ft overcast
- Temperature: 70 °F, dew point 61 °F
- Altimeter: 30.00 inHg
- Observed at: ZZV, 20 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19860901043529A](https://openairdocs.org/incident/19860901043529A), Sep 1, 1986: Enstrm F28C, Coshocton, OH, Substantial damage. The pilot overboosted the engine on takeoff which caused rotor RPM to decay and prevented climbout.

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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