# NTSB SEA94LA172: Pitts S1, Heber City, UT, July 5, 1994

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 5, 1994, 16:17 local (22:17 UTC)
- Place: Heber City, UT
- Coordinates: 40.429176, -111.189704 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.4292&lon=-111.1897&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report December 2, 1994
- Report: Approved by Office Director
- NTSB case key (mKey): 41969
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA94LA172
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41969/pdf
- Page: https://openairdocs.org/ntsb/SEA94LA172

## Probable cause

FAILURE OF MAIN LANDING GEAR AXLE HARDWARE.  FACTORS INCLUDE COLLAPSE OF MAIN LANDING GEAR STRUT.

## Sequence of events

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

- Main gear collapsed, landing - roll
  - landing gear,axle - separation (cause)
  - landing gear,main gear strut - overload (contributing factor)

## Analysis

THE PILOT STATED THAT HE LANDED SOMEWHAT HARD ON THE MAIN LANDING GEAR, RECORDING 2 G'S ON HIS ACCELEROMETER.  THE RIGHT MAIN LANDING GEAR WHEEL AND AXLE SEPARATED AND THE LANDING GEAR STRUT COLLAPSED.  POST-CRASH INSPECTION REVEALED THAT THE FOUR ATTACHMENT BOLTS WERE EXCESSIVELY WORN AND WERE APPARENTLY IMPROPERLY TORQUED.

## Factual narrative

On July 5, 1994, approximately 1617 mountain daylight time, an experimental Pitts S-1 was substantially damaged during roll out when the right wheel/axle attachment hardware failed after landing at Heber City, Utah.  The private pilot, who owned the aircraft, was uninjured.  Visual meteorological conditions prevailed for the flight, which originated at Heber City at 1601. There was no fire and no report of an ELT actuating.

FAA inspectors noted that the nuts and bolts securing the axle to the aircraft were excessively worn, and indicated that the nuts had sheared their threads before separating.  The pilot noted that four 1/4-20 bolts failed, causing wheel separation and subsequent gear failure, and indicated that the bolts had not been correctly torqued.

## Aircraft

- Registration: CGPUR (not matched to a registry record)
- Reported make and model: PITTS S1
- Category: Airplane, amateur-built
- Serial number: R-2
- Engines: LYCOMING O-360-A1A 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Burke, Jonathon
- Registered owner: Brian Bennett
- Airworthiness certificate: Special, Experimental (Special)
- Airport: 36U, Heber Valley, runway 21, 6,900 × 75 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 38; private; airplane ratings: single-engine land, multi-engine land; medical: class 1, valid medical--no waivers/lim.; seat: front; flight hours: 894 total, 820 as pilot in command, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 210° at 18 knots, gusting 40
- Visibility: 30 statute miles
- Lowest ceiling: none
- Temperature: 79 °F
- Altimeter: 29.00 inHg

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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