- Date
- April 30, 1992, 13:25 local (17:25 UTC)
- Place
- Mount Zion, KY
- Injuries
- 3 uninjured
- Damage
- Substantial damage
- Phase of flight
- Enroute
- Aircraft
- N97BRMcdonnell Douglas 500E
- Weather
- Visual (VMC) · Day
- Status
- Completed · report May 26, 1993
- Report
- Approved by Office Director
- Case key
- 37075
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
An in-flight separation of the tail rotor assembly as the result of the loss of an abrasion strip from the leading edge of one of the tail rotor blades, which induced vibrational stresses high enough to initiate fatigue failure in the tail rotor gear box mounting studs.
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
While flying in a cruise configuration at 1500 feet mean sea level, and about 10 minutes into the flight the helicopter started to vibrate. The pilot elected to make a forced landing in the most suitable area available. During the descent the vibration continued to worsen. At about 5 feet above the selected landing site the pilot heard a loud bang, the helicopter yawed to the right and pitched nose down. The pilot lowered the collective and put the helicopter on the ground. Metallurgical examination determined that the loss of the abrasion strip from the leading edge of tail rotor blade s/n 5086 induced vibrational stresses that were high enough to initiate fatigue failure in the tail rotor gear box mounting studs which resulted in the separation of the gear box assembly from the helicopter.
Aircraft
- Registration
- N97BR
- Reported as
- Mcdonnell Douglas 500E
- Category
- Helicopter
- Serial number
- 145E
- Airframe hours
- 1,350
- Engine
- Allison 250-C-20D, 420 horsepower, turbo shaft
- Damage
- Substantial damage
- Flight
- Public aircraft · Part 91
- Operator
- US Customs Service
- Registered owner
- US Customs Service
- Airworthiness certificate
- Standard, Normal
- Last inspection
- 100 hour · January 2, 2000 · 59 hours before
- Departed
- CVG · Cincinnati, OH
- Destination
- CVG
- Flight plan
- Company VFR
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 37
- Certificates
- Flight instructor, Airline transport, Commercial
- Airplane ratings
- Single-engine sea, Multi-engine sea, Single-engine land, Multi-engine land
- Instrument ratings
- Helicopter, Airplane
- Medical
- Class 1, Valid Medical--no waivers/lim.
- Seat
- Right
- Flight hours
- 5,750 total · 500 in this make and model · 4,700 as pilot in command · 150 in the last 90 days · 50 in the last 30 days · 6 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- Calm
- Visibility
- 25 statute miles
- Lowest ceiling
- None
- Temperature
- 75 °F
- Altimeter
- 30.00 inHg