- Date
- June 19, 1995, 14:40 local (19:40 UTC)
- Place
- Elkhorn, WI
- Injuries
- 2 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N470RABell 47J2A
- Weather
- Visual (VMC) · Day
- Status
- Completed · report March 6, 1996
- Report
- Approved by Office Director
- FAA report
- 19950619022669A
- Case key
- 9916
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
loss of power as a result of an intake valve failure due to improper maintenance performed during the major engine overhaul, and pilot misjudgment of the flare during autorotation.
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 pilot reported that he was cruising at about 1,000 feet when the engine lost power. An autorotation was initiated. During the landing phase (cyclic flare), the main rotor struck the tailrotor drive shaft. An examination of the engine revealed that the number two cylinder intake valve had failed in the top radius (neck area) of the valve keeper recess, causing damage to the cylinder combustion chamber and piston. An inspection of the engine logbooks indicated that an identical failure had occurred eight hours previously. Further inspection revealed that the major engine overhaul, which had been conducted 27 hours prior to the accident, had not been performed in accordance with the manufacturer's procedures and specifications.
Factual narrative
On June 19, 1995, at 1440 central daylight time, a Bell 47J2A helicopter, N470RA, sustained substantial damage as a result of an engine failure and subsequent autorotation. The accident took place near Elkhorn, Wisconsin. The airline transport pilot and the passenger reported no injury. The 14 CFR Part 91 flight departed East Troy Airport, East Troy, Wisconsin, on a local flight. Visual meteorological conditions prevailed and no flight plan was filed.
The pilot reported that he was cruising at about 1,000 feet above ground level when the engine failed. An autorotation was initiated. During the landing phase (cyclic flare), the main rotor struck the tailrotor drive shaft.
An examination of the engine revealed that the number two cylinder intake valve had failed in the top radius (necked area) of the valve keeper recess, causing damage to the cylinder combustion chamber and piston. An inspection of the engine logbooks indicated that an identical failure had occurred eight hours previously. The first failure occurred on a factory new cylinder assembly, and the second on a "used" cylinder of undetermined time in service. Further inspection revealed that the major engine overhaul, which had been conducted 27 hours prior to the accident, had not been performed in accordance with the manufacturer's procedures and specifications. (See attachments)
Aircraft
- Registration
- N470RA
- Reported as
- Bell 47J2A
- Category
- Helicopter
- Serial number
- 3719
- Airframe hours
- 6,100
- Engine
- Lycoming VO-540-B1B3, 305 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Personal · Part 91
- Registered owner
- John M. Wilson
- Airworthiness certificate
- Standard, Normal
- Last inspection
- Annual · May 30, 1995 · 27 hours before
- Departed
- 57C · East Troy, WI
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 40
- Certificate
- Airline transport
- Airplane ratings
- Multi-engine land, Single-engine land
- Instrument ratings
- Helicopter, Airplane
- Medical
- Class 1, Unknown
- Seat
- Right
- Flight hours
- 9,600 total · 200 in this make and model · 7,200 as pilot in command · 90 in the last 90 days · 30 in the last 30 days · 6 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 300° at 10 knots
- Visibility
- 8 statute miles
- Lowest ceiling
- None
- Temperature
- 90 °F
- Altimeter
- 30.00 inHg
- Observed at
- UES, 28 nm away
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.