CHI07LA127 · Beech S35
Beech S35 · Accident: total loss of engine power (mechanical failure) en route
From M16 · Raymond, MS to Fort Dodge Regional Airport (FOD)
Event
- NTSB case
- CHI07LA127
- 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
Beech S35
- Aircraft type
- Beechcraft 35
- 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
- N8820M
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From M16 · Raymond, MSTo Fort Dodge Regional Airport (FOD), Fort Dodge, IA
- 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
- En route · cruise
- 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
- Company maintenance personnel › Maintenance, installation, improper
- Engine assembly › Undertorqued
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
he pilot reported that the engine was "operating normally" as he was flying at 6,500 feet mean sea level when the "engine blew up." He elected to execute a gear up forced landing to a corn field about two miles from the airport, but the airplane impacted a ditch during the emergency landing. The engine teardown inspection revealed a hole in the crankcase approximately 3 inches by 3 inches above the number 4 cylinder, which included the 11 and 1 o'clock deck studs. The number 4 cylinder had separated from the crankcase and the number 4 connecting rod was not attached to the number 4 crankshaft pin. The number 4 connecting rod and rod cap exhibited signatures that were consistent with an overload event that deformed and/or sheared the threads on the nuts and bolts. Cylinder number 4 deck stud nuts 6, 7, and 8 were reported missing from the engine at the accident scene, and subsequently found inside the engine cowling of the aircraft. Cylinder number 4 deck studs 6, 7, and 8 were securely attached to the engine crankcase and the threads were clean and undamaged. The 2 o'clock cylinder deck stud was fractured and missing. The remaining deck studs and thru-bolts all exhibited ductile fractures indicative of tensile overload. The other five cylinders' thru-bolt and deck stud break-away torque measurements were recorded for each thru-bolt and deck stud. The inspection revealed that numerous thru-bolts and studs had break-away torque values that did not comply with the manufacturer's limitations. The aircraft engine's logbook indicated that the engine received an annual maintenance inspection on February 16, 2005. The engine logbook entry stated, "Removed and overhauled all 6 cylinders. Installed new rings, ground valves, cleaned and gapped spark plugs." The tach time indicated 5380.5 hours at the time of the annual inspection. At the time of the accident, the tach time was 5,662.24 hours, 281.74 hours since the cylinders had been replaced.
Probable cause
Improper maintenance by maintenance personnel by not properly torquing cylinder thru-bolts. The loose stud nuts which resulted in the separation of the cylinder and the crop and ditch were factors.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI07LA127
- Event ID
- 20070509X00537
- Case number
- CHI07LA127
- 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: b5b768147f36e71b4bc4e134cde15568d16c5f1cee37fe3eaf3b8b584973b656; retrieved 2026-09-22T03:51:54.041Z.