Flight 403 · Boeing B-727-200
Boeing B-727-200 · Incident: main gear collapsed while standing
From Indianapolis International Airport (IND) to Harry Reid International Airport (LAS)
Event
- NTSB case
- CHI97IA205
- 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
- Instrument Meteorological Cond
Boeing B-727-200
- Aircraft type
- Boeing 727
- 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
- N770AT
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Indianapolis International Airport (IND)To Harry Reid International Airport (LAS), Las Vegas, NV
- 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
- Standing
- 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
- Company maintenance personnel › Maintenance, installation, improper
- Landing gear, main gear attachment › Fractured
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
While the aircraft was being loaded with passengers, the flight engineer found that the right main landing gear had partially collapsed. The fractured right main landing gear had recently been overhauled and had accumulated 51 cycles and 126 hours since installation 21 days prior to the fracture. An examination was made of the aft portion of the upper and lower lugs of the trunnion. Chromium plating was apparent on sections of the trunnion where the overhaul manual stated that 'No Chrome' was to be applied. The spherical bearing assembly, locking bolt and anti-rotation washer were also examined. For normal assembly, the aft trunnion of the gear is inserted into the inner diameter of the wing mounted spherical bearing. The spherical bearing that contacted the trunnion journal had an inner diameter which measured approximately 3.50 inches. The aft trunnion journal of the failed landing gear had an outer diameter that measured approximately 3.25 inches. During landing gear replacement, the maintenance procedures require that the proper sized spherical bearings, either 3.50 inch or the 3.25 inch inner diameter, be matched with the appropriate outer cylinder aft trunnion outside diameter.
Probable cause
the improper installation of the incorrect spherical bearing by the company's maintenance personnel. A factor was the improper plating of the trunnion with chromium by the landing gear overhaul facility.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI97IA205
- Event ID
- 20001208X08312
- Case number
- CHI97IA205
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- 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: 3ff1aa82cbdd68c866f055d10a73b2a3b9a9cd0461d10bb615644153ae50d02e; retrieved 2026-09-18T17:29:04.641Z.