# NTSB MIA88LA186: Continental Copters MK6B, N9080T, Callahan, FL, June 1, 1988

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: June 1, 1988, 19:00 local (23:00 UTC)
- Place: Callahan, FL
- Coordinates: 30.560214, -81.830902 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=30.5602&lon=-81.8309&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report July 21, 1989
- Report: Approved by Office Director
- NTSB case key (mKey): 32189
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA88LA186
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/32189/pdf
- Page: https://openairdocs.org/ntsb/MIA88LA186

## Sequence of events

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

- Loss of engine power(total) - mech failure/malf, maneuvering - aerial application
  - accessory drive assy,drive gear - fatigue (cause)
  - accessory drive assy,drive gear - separation (cause)
  - maintenance,installation - improper, other maintenance personnel (cause)
- Forced landing, descent - emergency
  - autorotation - performed, pilot in command
- Hard landing, landing - flare/touchdown
  - flare - improper, pilot in command (contributing factor)

## Analysis

WHILE MANEUVERING THE HELICOPTER DURING AN AERIAL APPLICATION FLT THE ENG QUIT. DURING THE AUTOROTATIVE LANDING THE HELICOPTER LANDED HARD. EXAMINATION OF THE ENG REVEALED THE ACCESSORY DRIVE GEAR, WHICH IS ATTACHED TO THE CRANKSHAFT BY 6 AN-4A BOLTS WITH THE TORQUE TRANSMITTED TO THE GEAR THROUGH 3 PRESS-FIT DOWEL PINS, SEPARATED WHEN THE BOLTS FAILED DUE TO FATIGUE, RESULTING IN THE TOTAL LOSS OF ENG POWER. THERE WAS NO EVIDENCE THAT THE DOWEL PINS WERE INSTALLED. ACCORDING TO THE ENG MANUFACTURER, THE DOWEL PINS ARE THE PRINCIPAL TORQUE CARRYING MECHANISM OF THE ACCESSORY DRIVE GEAR.

## Aircraft

- Registration: [N9080T](https://openairdocs.org/deregistered/N9080T-2014-06-16), registration cancelled 2014-06-16, S/N CCI-76-4, built 1976 (OpenAirDocs)
- Reported make and model: Continental Copters MK6B
- Registry model: [Continental Copters TOMCAT MK6B](https://openairdocs.org/model/continental-copters-tomcat-mk6b) (registry code 2390202) (OpenAirDocs)
- Registry engine: [Lycoming VO-435 series](https://openairdocs.org/engine/lycoming-vo-435-series) (registry code 41525, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: CCI-76-4
- Airframe hours: 5500
- Engines: LYCOMING VO-435-B1A 265 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Registered owner: Cecil G. Register
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, June 8, 1987, 580 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 36; commercial; airplane ratings: single-engine land; medical: class 2, valid medical--no waivers/lim.; seat: center; flight hours: 10,000 total, 9,000 in this make and model, 9,500 as pilot in command, 110 in the last 90 days, 25 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 130° at 5 knots
- Visibility: 6 statute miles
- Lowest ceiling: none
- Temperature: 77 °F, dew point 66 °F
- Altimeter: 29.00 inHg
- Observed at: CRG, 19 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 19880601060419A](https://openairdocs.org/incident/19880601060419A), Jun 1, 1988: Tomcat OH13HMK6B, Callahan, FL, Substantial damage. Engine quit on spray run. Landed hard. TO0 low to autorotate. Accessory drive gear failed. Dowel pins not installed

## Other investigations on N9080T (2)

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.

- [NTSB CHI03LA204](https://openairdocs.org/ntsb/CHI03LA204), Jul 9, 2003: Continental Copters MK6B (N9080T), Ft. Yates, ND, substantial damage. Probable cause: The inadvertent settling with power and unsuccessful remedial action by the pilot. A factor to the accident was the potato crop.
- [NTSB ATL83LA011](https://openairdocs.org/ntsb/ATL83LA011), Oct 15, 1982: Tomcat MK68 (N9080T), Cope, SC, destroyed

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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