Cessna 421 accident near Chesterfield, Missouri, May 23, 2007
On May 23, 2007 at about 8:40 pm local time, a Cessna 421, registered N4082L, was substantially damaged in an accident near Chesterfield, Missouri (Spirit Of St. Louis airport). It was a personal flight under general aviation rules (Part 91). 1 person was seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 23, 2007 · about 8:40 pm local time
- Place
- Chesterfield, Missouri · Spirit Of St. Louis
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 421 · all 421s on the register
- Registration
- N4082L · no longer on the register · serial 421-0082
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 15,450 hours in all; 1,200 in this make and model; 95 in the last 90 days; 33 in the last 30 days
- Last flight review: August 1, 2006
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: serious injuries
The aircraft
- Airframe total time: 2,835 hours
- Last inspection: annual inspection, September 1, 2006; 35 hours since
- Maximum gross weight: 6,840 lb
- Seats: 6
- Landing gear: retractable
- Engine: Continental GTSIO-520-D (piston); 0 hours total
The flight
- Departed from: SUS Chesterfield MO at 8:40 pm
- Destination: CPS Cahokia IL
- Flight plan: VFR then IFR
Weather at the time
- Light: daylight
- Wind: from 180° at 9 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 8,500 ft; scat at 6,500 ft
- Temperature: 84°F (29°C), dew point 57°F (14°C)
- Altimeter: 30.09 inHg
- Observation at 8:45 pm from SUS
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.