# NTSB CHI90LA261: Piper PA-601P, N321GB, Monroe, MI, September 11, 1990

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: September 11, 1990, 06:15 local (10:15 UTC)
- Place: Monroe, MI
- Coordinates: 41.909381, -83.379692 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.9094&lon=-83.3797&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report December 14, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 14774
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI90LA261
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/14774/pdf
- Page: https://openairdocs.org/ntsb/CHI90LA261

## Probable cause

A FATIGUE FRACTURE OF THE TORQUE LINK ON THE RIGHT LANDING GEAR STRUT SCISSOR ASSEMBLY.

## Sequence of events

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

- Airframe/component/system failure/malfunction, landing - roll
  - landing gear,main gear strut scissors - fatigue (cause)
- Loss of control - on ground/water, landing - roll
  - directional control - not possible, pilot in command (contributing factor)
- Main gear collapsed, landing - roll

## Analysis

THE PILOT FELT THE AIRPLANE PULL RIGHT AT TOUCHDOWN. COMBINED USE OF FLIGHT CONTROLS, LEFT BRAKE AND DIFFERENTIAL POWER REDUCED BUT DID NOT PREVENT A DRIFT OFF THE RUNWAY. A BROKEN TORQUE LINK ON THE RIGHT MAIN LANDING GEAR SCISSORS ASSEMBLY ALLOWED THE LOWER STRUT TO TURN OUT OF ALIGNMENT, SCRUBBING THE RIGHT MAIN TIRE SIDEWAYS THROUGHOUT THE LANDING ROLL. THERE HAVE BEEN 17 SIMILAR FAILURES SINCE 1985. THE MANUFACTURER HAS USED A REDESIGNED LINK IN NEW PRODUCTION SINCE 1982 WITHOUT FAILURE. SERVICE BULLETIN 746A, ISSUED 5/86, OFFERS A LINK REPLACEMENT.

## Aircraft

- Registration: N321GB (not matched to a registry record)
- Reported make and model: PIPER PA-601P
- Category: Airplane
- Serial number: 629-7963287
- Airframe hours: 2843
- Engines: LYCOMING IO-540-S1A5 290 horsepower reciprocating
- Damage: Substantial damage
- Flight: Part 135
- Registered owner: Grand Aire Express, Inc.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, August 13, 1990, 45 hours before
- Departed: RFD, ROCKFORD, IL
- Destination: D92, MONROE, MI
- Flight plan: IFR
- Airport: D92, Custer, runway 21, 5,000 × 100 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 24; airline transport, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 1,681 total, 90 in this make and model, 1,621 as pilot in command, 181 in the last 90 days, 61 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 30° at 9 knots
- Visibility: 7 statute miles
- Lowest ceiling: 2,300 ft overcast
- Temperature: 64 °F, dew point 55 °F
- Altimeter: 30.00 inHg
- Observed at: DTW, 17 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 19900911038889A](https://openairdocs.org/incident/19900911038889A), Sep 11, 1990: Piper PA60601P, Monroe, MI, Substantial damage. Right main strut scissors broke on touchdown allowed wheel to cock causing runway excursion. Torque link AD 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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