# NTSB LAX92IA390: McDonnell Douglas MD-11, N90187, Yuma, AZ, September 17, 1992

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: September 16, 1992, 22:20 local (Sep 17, 1992, 05:20 UTC)
- Place: Yuma, AZ
- Coordinates: 32.719715, -114.509422 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=32.7197&lon=-114.5094&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 8 uninjured
- Status: Completed, report September 14, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27461
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX92IA390
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27461/pdf
- Page: https://openairdocs.org/ntsb/LAX92IA390

## Probable cause

AN UNSTABLE INTERACTION BETWEEN THE CENTER BODY MAIN LANDING GEAR AND THE BRAKE SYSTEM.

## Sequence of events

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

- Other gear collapsed, landing - roll
  - landing gear,anti-skid brake system - erratic (cause)
  - acft/equip,inadequate design, manufacturer
  - landing gear,main gear strut scissors - failure,total
  - landing gear,main gear - collapsed

## Analysis

MCDONNELL DOUGLAS INSTRUMENTED A FLIGHT TEST MD11 TO EXPLORE TWO PREVIOUS IN SERVICE INCIDENTS OF CENTER MAIN BODY LANDING GEAR DRAG LINK FAILURES. THE TEST PROTOCOL WAS DESIGNED TO REPLICATE THE KNOWN CIRCUMSTANCES OF THE TWO IN SERVICE FAILURES. DURING THE LANDING ON THE TEST FLIGHT, A FAILURE OF THE DRAG LINK WAS INDUCED, WHICH ALLOWED THE CENTER MAIN BODY GEAR TO FOLD AFT DAMAGING THE WHEEL WELL AND ADJACENT SKIN PANELS. EXAMINATION OF THE INSTRUMENTATION DATA REVEALED THAT THE DRAG LINK FAILURE WAS THE RESULT OF A DYNAMIC INSTABILITY OF THE CENTER BODY GEAR DUE TO AN UNFAVORABLE INTERACTION BETWEEN THE CENTER BODY LANDING GEAR AND THE BRAKE CONTROL SYSTEM (INCLUDING THE ANTI SKID AND AUTO BRAKE SUB SYSTEMS). AS A CORRECTIVE ACTION, THE MANUFACTURER DEVELOPED A MODIFICATION TO THE ANTI SKID CONTROL UNIT.

## Aircraft

- Registration: N90187 (not matched to a registry record)
- Reported make and model: McDonnell Douglas MD-11
- Category: Airplane
- Serial number: 48437
- Engines: P&W PW4460 60000 lbs thrust turbo fan
- Damage: Minor damage
- Flight: Part 91
- Operator: Mcdonnel Douglass Corp
- Registered owner: Mcdonnel Douglass Corp
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, January 2, 2000
- Flight plan: IFR
- Airport: YUM, Yuma Intl, runway 21, 13,299 × 200 ft, concrete

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 47; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 15,000 total

## Weather

- Conditions: Visual (VMC), Night/bright
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 90 °F, dew point -0 °F

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Incident 19920916042139I](https://openairdocs.org/incident/19920916042139I), Sep 16, 1992: Doug MD11, Yuma, AZ, Minor damage. Main center gear folded aft after drag links failed due to abs vibration on experimental brake system test flight

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.