CHI07LA154 · Cessna 421
Cessna 421 · Accident: total loss of engine power (mechanical failure) during initial climb
From Spirit of St Louis Airport (SUS) to St Louis Downtown Airport (CPS)
Event
- NTSB case
- CHI07LA154
- 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
- Accident
- 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
- Unknown
- 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
- General aviation
- 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
Cessna 421
- Aircraft type
- Cessna 421
- 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
- N4082L
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Spirit of St Louis Airport (SUS), Chesterfield, MOTo St Louis Downtown Airport (CPS), Cahokia, IL
- 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 91: General Aviation
- 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
- Initial climb
- 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
- Total loss of engine power (mechanical failure)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Engine assembly, gear › Failure, total
- Engine assembly, gear › Worn
- Other maintenance personnel › Maintenance, compliance with ad, not performed
- Pilot in command › Emergency procedure, not followed
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
Shortly after takeoff the pilot experienced a loss of power on the right engine. He attempted to return to the airport to land, but determined that he was not going to reach the runway so he elected to land on a dirt field. He flew under power lines that were in his flight path and attempted to flare the airplane prior to it impacting the terrain. The airplane was equipped with Teledyne Continental GTSIO-520 engines. Post accident examination of the right engine revealed that all of the teeth on the starter adapter gear and several of the teeth on the crankshaft gear were missing. Several gear teeth and metal filings were located in the oil sump. The torsional damper to shaft gear woodruff key was sheared. The torsional damper was placed on a test bench to determine the damping time. The consecutive tests averaged a damping time of 6.9 seconds. The damping time of a new damper is min/max 1.5 to 3.125 seconds. Metallurgical examination revealed 15 starter gear teeth and 11 crankshaft gear teeth were fractured near their root. No indications of preexisting cracking were noted. At least two of the starter gear teeth and several of the crankshaft gear teeth displayed spalling and wear at the pitch line of the teeth. On June 13, 1994, Teledyne Continental issued a Mandatory Service Bulletin, MSB94-4, addressing the possible failure of the starter adapter gear and/or crankshaft gear on GTSIO-520 and GIO-550 engines. On October 31, 2005, Teledyne Continental issued revision, MSB94-4G. The service bulletin called for an inspection of the starter adapter viscous damper and shaft gear backlash every 100 hours of engine operation, and a visual inspection of the starter adapter shaft and crankshaft gear teeth for spalling, pitting, and wear, every 400 hours of engine operation. The Federal Aviation Administration (FAA) issued Airworthiness Directive (AD) 2005-20-04, effective November 1, 2005, requiring compliance with the Teledyne Continental Mandatory Service Bulletin. Maintenance records showed the mandatory service bulletin had been complied with when the right engine was overhauled and installed in March 2001. There was no indication in the maintenance records that either the mandatory service bulletin or the AD had been complied with since the engine was installed. The engine had a total time of 541.9 hours at the time of the accident. The pilot did not follow the published emergency procedures.
Probable cause
Maintenance personnel failed to comply with an Airworthiness Directive which resulted in the total failure of the starter adapter gear teeth and the crankshaft gear teeth and the pilot failed to follow the published emergency procedures. Contributing to the accident were the low altitude at which the loss of power occurred, the power lines, and the unsuitable terrain which prevented the pilot from adequately flaring the airplane and resulted in the subsequent hard landing.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI07LA154
- Event ID
- 20070525X00643
- Case number
- CHI07LA154
- 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, coordinates. 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: b5c7605338dd89097bf711d233119950a2a35704b74cca1e2181641ef7e92f81; retrieved 2026-09-21T08:48:38.759Z.