Forbes Field Airport
Aircraft Accident/Incident Report

Topeka, Kansas 66620
Friday, August 28, 1998 10:53 CDT

NTSB Narrative Summary Released at Completion of Accident

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.

NTSB Probable Cause Narrative

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.

Event Information

Type of Event Accident
Event Date 8/28/1998
Event Day of the Week Friday
Time of Event 1053
Event Time Zone Central Daylight Time
Event City TOPEKA
Event State KANSAS
Event Country --
Zipcode of the event site 66620
Event Date Year 1998
Event Date Month 8
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude --
Event Location Longitude --
Event Location Airport FORBES FIELD
Event Location Nearest Airport ID FOE
Indicates whether the acc/inc occurred off or on an airport On Airport
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation 1080
Weather Briefing Completeness Unknown
Investigator's weather source Weather Observation Facility
Time of the weather observation 1053 Central Daylight Time
Direction of event from weather observation facility (degrees) 0
Weather Observation Facility ID FOE
Elevation of weather observation facility 1080
Distance of event from weather observation facility (units?) 0
Time Zone of the weather observation CDT
Lighting Conditions Day
Lowest Ceiling Height 0
Lowest Non-Ceiling Height 0
Sky/Lowest/Cloud Conditions Clear
Sky Condition for Lowest Ceiling None
Visibility Runway Visual Range (Feet) 0
Visibility Runway Visual Value (Statute Miles) 0
Visibility (Statute Miles) 10
Air Temperature at event time (in degrees celsius) 26
Dew Point at event time (in degress fahrenheit) 20
Wind Direction (degrees magnetic) 300
Variable Wind Indicator Unknown
Wind Speed (knots) 5
Wind Velocity Indicator Unknown
Wind Gust Indicator Not Gusting
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) 30
Density Altitude (feet) --
Intensity of Precipitation Unknown
METAR weather report --
Event Highest Injury None
On Ground, Fatal Injuries 0
On Ground, Minor Injuries 0
On Ground, Serious Injuries 0
Injury Total Fatal --
Injury Total Minor --
Injury Total None 3
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 1066
NTSB Notification Source --
NTSB Notification Date Aug 28 1998 12:00AM
NTSB Notification Time 1130
Fiche Number and/or location -used to find docket information IMAGE
Date of most recent change to record Feb 23 2001 1:55PM
User who most recently changed record dbo
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N230H
NTSB Number CHI98LA342
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 91: General Aviation
Type of Flight Plan filed None
Flight plan Was Activated? --
Damage Substantial
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name MBB
Aircraft Model BK-117
Aircraft Series Identifier BK-117
Aircraft Serial Number BK-117-A4
Certified Max Gross Weight 3200
Aircraft Category Helicopter
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 5
Number of Engines 2
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection AAIP
Date of Last Inspection Aug 13 1998 12:00AM
Airframe hours since last inspection 31
Airframe Hours 3928
ELT Installed Yes
ELT Activated Yes
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name DEBIS FINANCIAL SERVICES
Aircraft Owner Street Address 201 MERRITT 7, SUITE 700
Aircraft Owner City NORWALK
Aircraft Owner State CT
Aircraft Owner Country
Aircraft Owner Zipcode 06856
Operator is an individual? --
Operator Name ST. LOUIS HELICOPTERS
Operator Same as Owner? No
Operator Is Doing Business As --
Operator Address Same as Owner? No
Operator Street Address P.O. BOX 809
Operator City CHESTERFIELD
Operator State MO
Operator Country
Operator Zip code 63006
Operator Code
Owner has at least one certificate None
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation Unknown
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not --
Indicates Domestic or International Flight --
Operator carrying Pax/Cargo/Mail --
Type of Flying (Per_Bus / Primary) Unknown
Second Pilot on Board No
Departure Point Same as Event Yes
Departure Airport Code FOE
Departure City
Departure State
Departure Country
Departure Time 1040
Departure Time Zone CDT
Destination Same as Local Flt dest & departure same, accident can occur anywhere
Destination Airport Code
Destination City
Destination State
Destination Country
Specific Phase of Flight --
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Feb 23 2001 1:55PM
User who most recently changed record dbo
Since inspection or accident --
Event Location Runway Number and Location 0
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --