# NTSB MIA92LA111: Bell UH-1B, N4028F, La Belle, FL, April 22, 1992

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Limited investigation · Final report
- Date: April 22, 1992, 07:10 local (11:10 UTC)
- Place: La Belle, FL
- Coordinates: 26.6408, -81.340866 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=26.6408&lon=-81.3409&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 1 serious
- Status: Completed, report August 26, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 33085
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA92LA111
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/33085/pdf
- Page: https://openairdocs.org/ntsb/MIA92LA111

## Probable cause

IMPROPER PREFLIGHT BY THE PILOT-IN-COMMAND, IN HIS FAILURE TO IDENTIFY A CRACK IN A BRAZED AREA SURROUNDING AN ATTACH POINT ON THE AIR DIFFUSER. CONTRIBUTING TO THE ACCIDENT FOLLOWING THE LOSS OF ENGINE POWER WAS OBSTACLES THAT WERE AHEAD OF THE FLIGHT PATH.

## Sequence of events

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

- Loss of engine power(partial) - mech failure/malf, maneuvering - aerial application
  - bleed air system,fittings - fatigue
  - aircraft preflight - inadequate, pilot in command (cause)
  - bleed air system,fittings - failure,total
- Hard landing, landing - flare/touchdown
  - unsuitable terrain or takeoff/landing/taxi area - encountered, pilot in command (contributing factor)
- Roll over, other
- Nose over, other

## Analysis

THE PLT STATED THAT THE FLT PATH OF THE HELICOPTER WAS PERPENDICULAR TO POWER LINES THAT WERE AHEAD.  THE FLIGHT CONTINUED AND HE FURTHER STATED THAT HE HEARD A LOUD EXPLOSION & THE ENG QUIT.  HE PULLED THE COLLECTIVE CONTROL & CLEARED THE POWER LINES THEN LOWERED IT, & PRIOR TO IMPACT WITH THE GROUND, PULLED THE COLLECTIVE CONTROL TO CUSHION THE IMPACT.  THE HELICOPTER LANDED HARD, BOUNCED, TOUCHED DOWN, ROLLED OVER ON THE LT SIDE, THEN NOSED OVER & CAME TO REST INVERTED.  A SMALL FIRE WAS EXTINGUISHED BY SEVERAL INDIVIDUALS WHO RESPONDED TO THE ACCIDENT SITE.  THE ENG WAS REMOVED & SENT TO THE MANUFACTURER'S FACILITY FOR EXAMINATION.  EXAM OF THE ENG REVEALED THAT A MOUNTING BOSS ON THE AIR DIFFUSER FAILED DUE TO FATIGUE.  THE LINE ATTACHED TO THE BOSS WAS THE INTERSTAGE BLEED AIR LINE.  ALSO, A POWER TURBINE BLADE FAILED DUE TO FATIGUE.  REVIEW OF THE ENG LOGBOOKS REVEALED THAT THIS ENG WAS REMOVED FROM ANOTHER HELICOPTER & INSTALLED IN THIS HELICOPTER 6 DAYS PRIOR TO THE ACCIDENT.  THE ENG HAD ACCUMULATED ABOUT 10 HRS SINCE THEN & 703 HRS SINCE MAJOR OVERHAUL. ACCORDING TO THE ENG DAILY INSPECTION CHECKLIST, THE AIR DIFFUSER EXTERNAL VANE BRAZEMENTS SHOULD BE CHECKED FOR CRACKS.

## Aircraft

- Registration: [N4028F](https://openairdocs.org/deregistered/N4028F-1995-10-03), registration cancelled 1995-10-03, S/N 621948HC (OpenAirDocs)
- Reported make and model: BELL UH-1B
- Registry model: [Bell / Colony Services UH-1B](https://openairdocs.org/model/bell-colony-services-uh-1b) (registry code 118141D) (OpenAirDocs)
- Category: Helicopter
- Serial number: 62-1948HC
- Airframe hours: 6979
- Engines: LYCOMING TH53-L110 1100 horsepower turbo shaft
- Damage: Substantial damage
- Fire: On-Ground
- Flight: Aerial application, Part 137
- Operator: Colony Services, Inc.
- Registered owner: Helicorp, Inc.
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, March 27, 1992, 31 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 47; commercial, private; airplane ratings: multi-engine land, single-engine land; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 17,000 total, 7,500 in this make and model, 16,800 as pilot in command, 75 in the last 90 days, 25 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 70 °F

## 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 19920422015369A](https://openairdocs.org/incident/19920422015369A), Apr 22, 1992: Bell UH1B, La Belle, FL, Substantial damage. Loud bang on takeoff and power loss, hard landing clearing wires. Tumbled. Air diffuser and turbine blade failed.

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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