- Date
- August 13, 1991, 18:15 local (Aug 14, 1991, 01:15 UTC)
- Place
- San Jose, CA
- Injuries
- 1 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N3028CBeech J35
- Weather
- Visual (VMC) · Day
- Status
- Completed · report March 10, 1993
- Report
- Approved by Office Director
- FAA report
- 19910813033929A
- Case key
- 27327
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The failure of the crankshaft counterweight retaining clip due to improper maintenance installation of the part.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
The engine was overhauled and modified about six operating hours prior to the accident with a new type of cam shaft under the provisions of a supplemental type certificate. The pilot said he was in level cruise when he heard a loud bang emanate from the engine concurrently with it stopping. An initial inspection of the aircraft on site by FAA inspectors revealed that oil covered the wind shield. The number two cylinder rod was observed to be protruding from a hole in the top of the engine case. One counter weight assembly was found missing from the crankshaft counterweight blade. The missing counterweight, cover plates, retaining cir-clips, and associated bushings were found in the oil pan. Optical examination of the recovered pieces revealed that the retaining cir-clip failed, allowing the counter weight pin and the weight itself to separate from the crankshaft. The inspector determined that the cir-clip had been installed backwards.
Aircraft
- Registration
- N3028C
- Reported as
- Beech J35
- Category
- Airplane
- Serial number
- D-5693
- Airframe hours
- 3,685
- Engine
- Continental IO-470-C, 250 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Operator
- Dtb Aviation
- Registered owner
- Dtb Aviation
- Airworthiness certificate
- Special, Experimental (Special)
- Last inspection
- Annual · February 13, 1991 · 26 hours before
- Destination
- 307 · Hollister, CA
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 33
- Certificate
- Commercial
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 2, Valid Medical--w/ waivers/lim
- Seat
- Left
- Flight hours
- 676 total · 71 in this make and model · 572 as pilot in command · 30 in the last 90 days · 8 in the last 30 days · 2 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 300° at 12 knots
- Visibility
- 25 statute miles
- Lowest ceiling
- None
- Temperature
- 90 °F, dew point 68 °F
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.
Other investigations on N3028C · 2
Matched to the same aircraft by N-number and date.