# NTSB ATL83LA252: Sikorsky UH-19D, N37785, Thomasville, GA, July 4, 1983

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 4, 1983, 11:45 local (15:45 UTC)
- Place: Thomasville, GA
- Coordinates: 30.970884, -84.050865 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=30.9709&lon=-84.0509&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 6110
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL83LA252
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/6110/pdf
- Page: https://openairdocs.org/ntsb/ATL83LA252

## Sequence of events

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

- Airframe/component/system failure/malfunction, maneuvering - aerial application
  - fluid - incorrect (cause)
  - rotor drive system,clutch assembly - disabled (cause)
- Forced landing, landing
  - autorotation - performed, pilot in command
  - terrain condition - high obstruction(s) (contributing factor)
  - maneuver - performed, pilot in command
  - flare - not possible, pilot in command

## Analysis

THE HELICOPTER WAS ON A SWATH RUN AT ABOUT 5 FT AGL & WAS APPROACHING HI OBSTRUCTIONS WHEN THE PLT NOTED THAT THE NEEDLES SPLIT, THE ENG RPM INCREASED & THE MAIN ROTOR RPM BEGAN DECREASING. THE PLT TURNED TO AVOID THE OBSTRUCTIONS, BUT WAS UNABLE TO LEVEL THE ACFT BEFORE GROUND IMPACT. IT HIT THE GROUND IN A RIGHT SIDE, TAIL LOW, ATTITUDE & ROTATED TO THE RIGHT AFTER THE MAIN ROTOR MADE GROUND CONTACT. AN INVESTIGATION REVEALED THE HYDROMECHANICAL CLUTCH HAD BEEN OVERHAULED & INSTALLED, 2.5 FLT HRS PRIOR TO THE ACCIDENT. NO UNUSUAL WEAR, DEFECTIVE PARTS NOR IMPROPER ALIGNMENT OF THE CLUTCH WAS FOUND. THE CLUTCH HAD BEEN LUBRICATED WITH AN UPDATED OIL. THE MILITARY HAD UPGRADE MIL-L-2105 LUBRICANT TO MIL-L-2105B & C WITH NEW ADDITIVES TO PREVENT LOCKUP OF ITS LIMITED SLIP DIFFERENTIALS ON NEWER HELICOPTERS. HOWEVER,THE ADDITIVES WERE NOT COMPATIBLE WITH UH-19D HYDROMECHANICAL CLUTCHES WHICH USED A METAL-TO-METAL PRINCIPLE. AFTER THE ACCIDENT, MIL-L-21260 TYPE 1, GRADE 30 OIL WAS MADE A SUBSTITUTE FOR MIL-L-2105A GRADE 80 OIL, WHICH WAS NO LONGER AVAIL

## Aircraft

- Registration: [N37785](https://openairdocs.org/deregistered/N37785-2014-12-17), registration cancelled 2014-12-17, S/N 57-5932, built 1957 (OpenAirDocs)
- Reported make and model: SIKORSKY UH-19D
- Registry model: [Sikorsky UH-19D](https://openairdocs.org/model/sikorsky-uh-19d) (registry code 814161G) (OpenAirDocs)
- Registry engine: [Wright R-1300 series](https://openairdocs.org/engine/wright-r-1300-series) (registry code 67060, reciprocating) (OpenAirDocs)
- Category: Helicopter
- Serial number: 57-5932
- Airframe hours: 2684
- Engines: WRIGHT R-1300-3D 800 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial application, Part 137
- Registered owner: Powers Crop Dusters, Inc.
- Airworthiness certificate: Special, Restricted (Special)
- Last inspection: Annual, March 11, 1983, 34 hours before
- Departed: TVI, THOMASVILLE, GA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 41; commercial; airplane ratings: single-engine land, multi-engine sea, single-engine sea, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 13,600 total, 600 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 20° at 8 knots
- Visibility: 15 statute miles
- Temperature: 90 °F, dew point 73 °F
- Altimeter: 30.00 inHg
- Observed at: ABY, 41 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 19830704027979A](https://openairdocs.org/incident/19830704027979A), Jul 4, 1983: Orlhel UH19DSKRSKY, Thomasville, GA, Substantial damage. Main rotor drive clutch disengaged on a spray run. Crash landed. Lubricant used a factor. Service bulletin issued.

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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