Accident MBB BK 117A-4 N230H,
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ASN Wikibase Occurrence # 75950
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Date:Friday 28 August 1998
Time:11:53 LT
Type:Silhouette image of generic BK17 model; specific model in this crash may look slightly different    
MBB BK 117A-4
Owner/operator:St. Louis Helicopters
Registration: N230H
MSN: BK-117-A4
Year of manufacture:1987
Total airframe hrs:3928 hours
Engine model:Lycoming LTS-101-650B1
Fatalities:Fatalities: 0 / Occupants: 3
Aircraft damage: Substantial
Location:Topeka, KS -   United States of America
Phase: Approach
Departure airport:(KFOE)
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
The accident occurred on a maintenance test flight after having had the No. 1 engine replaced. When returning from the flight a 'severe bump' and 'loud bang' were experienced followed by the helicopter rotating to the right. A pilot landed the helicopter in a field during which time it rolled over on its left side. Post accident inspection revealed the No. 1 engine cowling separated from the helicopter inflight. This damaged the main rotor blades which resulted in an imbalance and subsequent loss of the tail rotor gear box. Both Hartwell cowling latches appeared in the closed position; however, the aft latch was not damaged as was the forward latch. The manufacturer is aware of similar problems and has issued service bulletins addressing the problems. The latest service bulletin, SB-MBB-BK 117-20-109, had not been incorporated on the accident helicopter.

Probable Cause: the pilot's failure to assure the engine cowling was secured during the aircraft preflight which resulted in the cowling separating from the helicopter and damaging the main rotor and tail rotor system. Factors associated with the accident were the cowling not being secured and inadequate design of the latching system by the manufacturer.

Accident investigation:
Investigating agency: NTSB
Report number: CHI98LA342
Status: Investigation completed
Duration: 2 years and 5 months
Download report: Final report



Revision history:

27-Jul-2010 11:03 Alpine Flight Added
19-Aug-2010 13:58 TB Updated [Aircraft type, Operator]
20-Nov-2012 12:41 TB Updated [Nature, Departure airport, Destination airport, Source, Damage, Narrative]
20-Nov-2012 12:42 TB Updated [Source]
21-Dec-2016 19:25 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
06-Apr-2024 11:22 ASN Update Bot Updated [Time, Cn, Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative, Accident report]

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