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Simmons Airlines ATR 42 incident

3 Apr 1996 · Traverse City, MI, United States

ATR 42 · Incident: main gear collapsed during landing

From Chicago O'Hare International Airport (ORD) to Cherry Capital Airport (TVC)

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Event

NTSB case
CHI96IA125
Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
Incident
InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
Completed
API-reported fatalities
0 · all aircraft and ground
Ground fatalities
0
OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
Airline
WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
Visual Meteorological Cond

ATR 42

Aircraft type
ATR 42
Category
Airplane
RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
N421MQ
Onboard fatalities
Unknown
Route
From Chicago O'Hare International Airport (ORD), Chicago, ILTo Cherry Capital Airport (TVC)
Aircraft age
Not recorded
Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
Part 121: Air Carrier
Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
Landing · landing roll
First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
Main gear collapsed
DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
Minor

Cause areas

  • Landing gear, main gear › Corroded
  • Landing gear, main gear › Fatigue
  • Other maintenance personnel › Improper use of procedure
  • Other maintenance personnel › Maintenance, overhaul, improper

Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.

NTSB narrative

During landing rollout, the left main landing gear collapsed, and the aircraft skidded to a stop. Examination of the landing gear revealed that the barrel lugs (used to attach the swinging lever to the main landing gear barrel) had failed. The fracture of the outboard lower lug exhibited clam shell marks typical of a fatigue crack. The fatigue crack emanated from a corrosion pit in the bore of the lug. The four bushings for the lower lugs of the barrel (replaced during overhaul) did not have the proper interference fit. The bushings did not have the proper applications of corrosion preventative applied to the surface of the bushings. Primer paint had not been applied during overhaul, and Mastinox was used instead of the wet primer that the manufacturer's procedures specified. During the course of the investigation, nine landing gears (with various numbers of total cycles since overhaul or manufacture) were inspected. The inspections revealed torn or missing rubber sealant used on bushing flanges, corrosion in the lug bores, and corrosion on the lug faces.

Probable cause

improper use of procedures by maintenance personnel at an overhaul facility during overhaul of the landing gear, allowing corrosion to occur on the barrel lugs of the landing gear, which subsequently led to fatigue cracking of the lugs and eventual collapse of the gear.

Verbatim NTSB analysis and probable cause from the NTSB dataset

Sources

NTSB record CHI96IA125
Event ID
20001208X05524
Case number
CHI96IA125
Dataset
historical-pre2008
Source SHA-256
89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (5)
  • Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
  • Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
  • The date is the local date, which is the same as the UTC date the NTSB stores.
  • API snapshot SHA-256: d2e6aefa0f6a7bffa32599aec4a338e90359c4c804afb67ac5b4ac33bb30ffb7; retrieved 2026-09-18T17:52:12.947Z.
  • The NTSB's operator name is blank for N421MQ; the operator shown is the name the NTSB records it doing business as.