# NTSB FTW92FA197: Boeing A75, N62552, Cibolo, TX, July 31, 1992

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: July 31, 1992, 10:49 local (15:49 UTC)
- Place: Cibolo, TX
- Coordinates: 29.5701, -98.229553 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=29.5701&lon=-98.2296&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed, report June 30, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 18367
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW92FA197
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18367/pdf
- Page: https://openairdocs.org/ntsb/FTW92FA197

## Probable cause

FAILURE OF THE ENGINE CRANKSHAFT DUE FATIGUE AND THE RESULTANT COLLAPSING OF THE LEFT WING.

## 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, approach - vfr pattern - downwind
  - engine assembly,crankshaft - failure,total (cause)
  - engine assembly,crankshaft - fatigue (cause)
- Loss of control - in flight, approach - vfr pattern - downwind
  - wing,bracing strut - fractured
  - wing,bracing wire - sheared
  - wing - collapsed (cause)
  - aircraft control - not possible, pilot in command
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE COMMERCIAL PILOT HAD BEEN TROUBLESHOOTING A VIBRATION PRESENT IN HIS AIRPLANE FOR THE LAST 10 FLIGHT HOURS. AFTER THE BLADE ANGLES ON THE PROPELLER BLADES WERE REALIGNED HE FLEW THE AIRPLANE TO CHECK THE VIBRATION LEVEL. WHILE ON A LEFT DOWNWIND, THE PROPELLER SEPARATED FROM THE ENGINE AND SEVERED A WING STRUT AND PORTION OF THE LEFT WING. AFTER BOTH OF THE BIPLANE'S LEFT WINGS COLLAPSED, THE AIRPLANE ENTERED A LEFT VERTICAL SPIRAL AND IMPACTED IN AN OPEN PASTURE. SEPARATION OF THE CRANKSHAFT WAS A RESULT OF FATIGUE ORIGINATING IN THE THREADS AT A POSITION NORMALLY IN LINE WITH THE AFT FACE OF THE THRUST NUT. THE THRUST NUT ALSO FAILED IN FATIGUE. NUT CONFIGURATION WAS DIFFERENT FROM THE CONFIGURATION INDICATED IN THE ENGINEERING DRAWING. HOWEVER, IT WAS NOT ESTABLISHED IF THIS WAS A CONTRIBUTING FACTOR TO THE FAILURE. THERE WAS ALSO NO EVIDENCE OF OVER TORQUE DURING INSTALLATION.

## Aircraft

- Registration: [N62552](https://openairdocs.org/aircraft/N62552), registered now, S/N 75-3190, built 1940 (OpenAirDocs)
- Reported make and model: BOEING A75
- Registry model: [Boeing A75](https://openairdocs.org/model/boeing-a75) (registry code 1380108) (OpenAirDocs)
- Registry engine: [Continental W670 series](https://openairdocs.org/engine/continental-w670-series) (registry code 17018, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 75-3190
- Airframe hours: 601
- Engines: CONTINENTAL W670-6A 220 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: Perdue, Harold F.
- Registered owner: Perdue, Harold F.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, December 6, 1991, 25 hours before
- Departed: 15R
- Destination: 15R

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 70; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: front; toxicology performed; flight hours: 5,500 total, 1,000 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 190° at 9 knots
- Visibility: 7 statute miles
- Lowest ceiling: 25,000 ft broken
- Temperature: 82 °F, dew point 73 °F
- Altimeter: 30.00 inHg
- Observed at: RND, 22 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 19920731028449A](https://openairdocs.org/incident/19920731028449A), Jul 31, 1992: Boeing A75, Cibolo, TX, Destroyed, 1 fatal. Inflight breakup after propeller assembly separated and severed a wing strut. Forward end crankshaft had broken.

## Other investigations on N62552 (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 UNK64X3159](https://openairdocs.org/ntsb/UNK64X3159), Aug 1, 1964: Boeing A75N1 (N62552), San Antonio, TX, destroyed, 1 fatal

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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