# NTSB NYC83FA121: Mooney M-20K, N231HT, Old Lyme, CT, May 20, 1983

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: May 20, 1983, 14:20 local (18:20 UTC)
- Place: Old Lyme, CT
- Location: 41.3159° N, 72.3290° W: Placed by OpenAirDocs: center of Old Lyme, CT, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=41.3159&lon=-72.3290&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 35046
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC83FA121
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/35046/pdf
- Page: https://openairdocs.org/ntsb/NYC83FA121

## Sequence of events

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

- Airframe/component/system failure/malfunction, climb - to cruise
  - vacuum system - failure,total (cause)
  - flight/nav instruments,attitude gyro - failure,total (contributing factor)
  - flight/nav instruments,directional gyro - failure,total (contributing factor)
- Loss of control - in flight, maneuvering
  - proper altitude - not maintained, pilot in command (cause)
  - directional control - not maintained, pilot in command (cause)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE ACFT COLLIDED WITH THE GROUND IN IMC AFTER THE PLT REPORTED HE LOST HIS VACUUM INSTRUMENTS. THE FLT ORIGINATED AT MATTITUCK, NY WITH A DESTINATION OF LEBANON, NH. AFTER DEPARTURE THE PLT WAS CLEARED TO CLIMB TO 7000 FT. THE INSTRUMENTRATED PILOT WAS ON AN IFR FLT PLAN. ABOUT 8 MINUTES AFTER DEPARTURE THE PILOT RADIOED THAT HE HAD EXPERIENCED A LOSS OF VACUUM AND HIS ARTIFICIAL HORIZON WAS INOPERATIVE. HE ALSO STATED HE HAD NO AUTOPILOT AND REQUESTED RADAR VECTORING. HE WAS GIVEN A HEADING OF 050 FOR RADAR VECTORING TO NORWICH VOR. ABOUT 2 MINUTES LATER THE PILOT RADIOED HE WAS 'IN TROUBLE AND IN A DIVE.' ONE MIN LATER HE RADIOED 'ONE THOUSAND FT I AM IN DEEP TROUBLE HERE.' THIS WAS THE LAST RADIO CALL FROM THE PLT. WITNESSES IN THE AREA HEARD & SAW THE ACFT COME OUT OF THE CLOUDS AT 200-300 FT & THEN CLIMB BACK INTO THE FOG BANK. SHORTLY THEREAFTER, A 'WHISTLING DIVE' WAS HEARD FOLLOWED BY THE SOUND OF A CRASH. THE WX IN THAT AREA WAS DESCRIBED AS FOG, LIGHT RAIN, & OVERCAST. EXAM OF THE ACFT WRECKAGE REVEALED THAT THE VACUUM PUMP FAILED.

## Aircraft

- Registration: [N231HT](https://openairdocs.org/deregistered/N231HT-2017-04-04), registration cancelled 2017-04-04, S/N 25-0267, built 1979 (OpenAirDocs)
- Reported make and model: MOONEY M-20K
- Registry model: [Mooney M20K](https://openairdocs.org/model/mooney-m20k) (registry code 5870220) (OpenAirDocs)
- Registry engine: [Continental TSIO-360 series](https://openairdocs.org/engine/continental-tsio-360-series) (registry code 17019, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 25-0267
- Engines: CONTINENTAL TSIO-360-GB 210 horsepower reciprocating
- Damage: Destroyed
- Fire: On-Ground
- Flight: Personal, Part 91
- Operator: Yale Grayson
- Registered owner: Arthur W. John
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, July 14, 1982
- Departed: MATTITUCK, NY
- Destination: LEB, LEBANON, NH
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 53; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; toxicology performed; flight hours: 3,900 total

## Weather

- Conditions: Instrument (IMC), Day
- Wind: 220° at 14 knots
- Visibility: 1 statute miles
- Lowest ceiling: 700 ft overcast
- Temperature: 54 °F
- Altimeter: 30.00 inHg
- Observed at: GON, 13 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 19830520020329A](https://openairdocs.org/incident/19830520020329A), May 20, 1983: Mooney M20K, Old Lyme, CT, Destroyed. Lost vacuum instruments due to a sheared vacuum pump shaft. Lost control of aircraft. No reference to a basic panel

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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