# N517S: Cessna 421A, registration cancelled 1991-04-01

- Type: Cancelled registration (FAA registry, deregistered aircraft)
- Cancelled: April 1, 1991
- Status when cancelled: Triennial form not returned
- Airframe: [Cessna 421A](https://openairdocs.org/model/cessna-421a) (registry code 2076012)
- Data sheets: [TCDS A7CE](https://openairdocs.org/tcds/A7CE) (OpenAirDocs)
- Serial number: 421A0002
- Type of aircraft: Fixed wing multi engine
- Certificate issued: October 28, 1986
- Last registry action: January 31, 1991
- Mode S code: A67D00
- Owner when cancelled: [Mamuzich Kenneth G](https://openairdocs.org/faa-owner/MAMUZICH%20KENNETH%20G)
- Location: [Missoula, MT](https://openairdocs.org/faa-place/MT/Missoula)
- Owner type: Individual
- Owner's area on the map: 46.8547° N, 114.0104° W: Placed by OpenAirDocs at the center of ZIP code 59801, within about 2 miles (OpenAirDocs). The owner's mailing address, not where the aircraft was based
- The mark today: https://openairdocs.org/aircraft/N517S
- FAA registry: https://registry.faa.gov/AircraftInquiry/Search/NNumberResult?nNumberTxt=517S
- Page: https://openairdocs.org/deregistered/N517S-1991-04-01

From the FAA registry file of November 5, 2026, cancelled registrations. Owners' street addresses are left out. The Mode S code belongs to the N-number, not the airframe.

ADs and bulletins for the Cessna 421A: https://openairdocs.org/model/cessna-421a.md

## NTSB investigations (1)

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 DEN88FA063](https://openairdocs.org/ntsb/DEN88FA063), Feb 4, 1988: Cessna 421A (N517S), Helena, MT, destroyed, 3 fatal

## FAA accident and incident reports (1)

From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [Accident 19880203002029A](https://openairdocs.org/incident/19880203002029A), Feb 3, 1988: Cessna 421A (N517S), Helena, MT, Destroyed, 3 fatal. Struck trees on mountainside on ILS approach at night in heavy snow. Co pilot at controls left seat. Acft burned.

## Other aircraft with N517S

- [Registered now](https://openairdocs.org/aircraft/N517S): Czech Sport Aircraft A S SPORTCRUISER, S/N C0534, built 2015

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