# NTSB NYC91LA040: Enstrom F-28C, N4953X, Easton, PA, November 28, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: November 28, 1990, 09:45 local (14:45 UTC)
- Place: Easton, PA
- Coordinates: 40.680198, -75.219512 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.6802&lon=-75.2195&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report February 12, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 36852
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC91LA040
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/36852/pdf
- Page: https://openairdocs.org/ntsb/NYC91LA040

## Probable cause

AN INFLIGHT FAILURE OF THE LEFT SIDE CABIN MOUNT BRACKET WHICH RESULTED IN A LOSS OF LATERAL CYCLIC CONTROL. FACTORS RELATED TO THE ACCIDENT WERE: AN INCOMPLETE INSPECTION OF THE HELICOPTER FOLLOWING A HARD LANDING WITH A BLADE STRIKE.

## Sequence of events

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

- Airframe/component/system failure/malfunction, cruise - normal
  - rotorcraft flight control,cyclic bellcrank - failure,total (cause)
  - maintenance,rebuild/remanufacture - improper, other maintenance personnel (cause)
  - maintenance,inspection - inadequate, other maintenance personnel (cause)
  - maintenance,replacement - not performed, other maintenance personnel (cause)
- Loss of control - in flight, cruise - normal
- Forced landing, descent - emergency
- Roll over, landing - flare/touchdown
  - aircraft control - not maintained, pilot in command
  - remedial action - not possible, pilot in command

## Analysis

IN CRUISE FLT THE HELICOPTER UNEXPECTEDLY ROLLED 90 DEGREES LEFT. THE PILOT AUTOROTATED TO A LANDING, ROLLING OVER UPON TOUCHDOWN. THE LEFT SIDE CABIN MOUNT BRACKET WHICH HOLDS THE INTERMEDIATE BELLCRANK FOR LATERAL CONTROL HAD FRACTURED. THE FRACTURE SURFACE BORE EVIDENCE OF OVERLOAD AND FATIGUE. THE BELLCRANK WAS TIGHT IN THE CABIN MOUNT BRACKET. IN ADDITION, THE RIGHT SIDE CABIN MOUNT BRACKET WHICH HOLD THE INTERMEDIATE BELLCRANK FOR FORE AND AFT CONTROL HAD A CRACK. THE FRACTURE SURFACE WAS TYPICAL OF OVERLOAD. THE HELICOPTER HAD PREVIOUSLY BEEN INVOLVED IN A HARD LANDING WITH A BLADE STRIKE ON THE TAIL BOOM. NO RECORDS WERE AVAILABLE TO INDICATE THE REPAIRS CONDUCTED. ACCORDING TO ENSTROM HELICOPTERS, THESE FRACTURES ARE TYPICALLY SEEN FOLLOWING A BLADE STRIKE. ACCORDING TO AN ENSTROM HELICOPTERS SERVICE LETTER, '...CYCLIC AND COLLECTIVE TORQUE TUBES, BELLCRANKS, AND FITTING...' ARE REQUIRED INSPECTIONS ITEMS FOLLOWING A BLADE STRIKE.

## Aircraft

- Registration: N4953X (not matched to a registry record)
- Reported make and model: ENSTROM F-28C
- Category: Helicopter
- Serial number: 469
- Airframe hours: 2450
- Engines: LYCOMING HIO-360-E1AD 205 horsepower reciprocating
- Damage: Destroyed
- Flight: Business, Part 91
- Operator: Jerry Engel
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, March 12, 1990, 25 hours before
- Destination: TTN, TRENTON, NJ

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 32; private; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 126 total, 107 in this make and model, 71 as pilot in command, 16 in the last 90 days, 3 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 240° at 8 knots
- Visibility: 3 statute miles
- Lowest ceiling: 4,500 ft overcast

## 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 19901128002069A](https://openairdocs.org/incident/19901128002069A), Nov 28, 1990: Enstrm F28C, Easton, PA, Substantial damage. Lost lateral control. Cut power autorotated and rolled over on flare. Cabinmount bracket failed. Bell crank rotated

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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