Probable cause
The in-flight separation of the left aft cluster fitting assembly following the loss of torque on the lock nut due to a manufacturing defect.
NTSB analysis
While the helicopter was hovering prior to departure for a routine training flight, a bolt and its associated hardware for the left aft cluster fitting of the tail boom assembly departed the helicopter. Subsequently, the instructor initiated a forced landing and the helicopter came to rest upright. Examination of the bolt and lock nut revealed incomplete threads at the pinch point of the locking stake due to a manufacturing defect. The bolt and lock nut assembly were installed as part of an aft cluster fitting modification that was performed about 4 months and 216 operational hours prior to the accident. As a result of the accident, the Federal Aviation Administration issued an Emergency Airworthiness Directive for owners to check the lock nuts.
Text from the NTSB. Open the NTSB docket for CEN10LA560 for the full record.
Event
- Date
- Sep 20, 2010
- Type
- Accident
- Place
- Schaumburg, Illinois
- Nearest airport
- Schaumburg Regional Airport (06C)
- Highest injury
- None
- Weather
- Visual (VMC)
- Light
- Day
Schweizer 269C
- N-number
- N34LB
- Category
- Helicopter
- Damage
- Substantial
- Operating rule
- Part 91 (general aviation)
- Purpose of flight
- Instructional
From the NTSB aviation accident database: N-registered aircraft, events since 2008, data through Oct 28, 2026. The file is published monthly, so the latest weeks are incomplete and recent records can change. The official source is the NTSB aviation investigation search. CheckAero is independent and not affiliated with the NTSB.