Unknown Airport
Aircraft Accident/Incident Report

Aguadilla, Puerto Rico 00662
Thursday, July 29, 1999 9:15 AST

NTSB Narrative Summary Released at Completion of Accident

While in cruise flight at 800 feet, the pilot heard a metal grinding noise followed by the engine failure warning. The pilot entered autorotation and during landing flare he was unable to arrest the descent, resulting in a hard landing and damage to the helicopter. Postcrash examination of the engine and engine systems showed no anomalies. Examination of the main transmission showed no damage which cause seizing of the transmission. Examination of the oil cooler blower assembly showed one impeller blade was fractured due to overload which opened a two inch gap in the impeller. The blower stopped spinning and sheared away from the adapter. The impeller shroud had abrasion damage and some minor areas of debris buildup. The oil cooler is driven by the main transmission.

NTSB Probable Cause Narrative

An unidentified foreign object passing through the oil cooler blower assembly resulting in fracture and seizure of the oil cooler blower, and slowing of the main transmission and main rotor, which resulted in the pilot being unable to arrest the descent during an autorotative landing.

Event Information

Type of Event Accident
Event Date 7/29/1999
Event Day of the Week Thursday
Time of Event 915
Event Time Zone Atlantic Standard Time
Event City Aguadilla
Event State PUERTO RICO
Event Country --
Zipcode of the event site 00662
Event Date Year 1999
Event Date Month 7
MidAir Collision Indicator No
On Ground Collision occurred ? Yes
Event Location Latitude --
Event Location Longitude --
Event Location Airport Unknown
Event Location Nearest Airport ID --
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation --
Weather Briefing Completeness Unknown
Investigator's weather source Weather Observation Facility
Time of the weather observation 850 Atlantic Standard Time
Direction of event from weather observation facility (degrees) 270
Weather Observation Facility ID BQN
Elevation of weather observation facility 238
Distance of event from weather observation facility (units?) 8
Time Zone of the weather observation AST
Lighting Conditions Day
Lowest Ceiling Height --
Lowest Non-Ceiling Height --
Sky/Lowest/Cloud Conditions Clear
Sky Condition for Lowest Ceiling None
Visibility Runway Visual Range (Feet) --
Visibility Runway Visual Value (Statute Miles) --
Visibility (Statute Miles) 14
Air Temperature at event time (in degrees celsius) 28
Dew Point at event time (in degress fahrenheit) 23
Wind Direction (degrees magnetic) 100
Variable Wind Indicator Wind direction could be determined
Wind Speed (knots) 10
Wind Velocity Indicator --
Wind Gust Indicator Not Gusting
Wind Gust (knots) --
Altimeter Setting at event time (in. Hg) 30.04
Density Altitude (feet) 1900
Intensity of Precipitation --
METAR weather report --
Event Highest Injury None
On Ground, Fatal Injuries --
On Ground, Minor Injuries --
On Ground, Serious Injuries --
Injury Total Fatal --
Injury Total Minor --
Injury Total None 1
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 15231
NTSB Notification Source --
NTSB Notification Date --
NTSB Notification Time --
Fiche Number and/or location -used to find docket information DMS
Date of most recent change to record Mar 30 2004 8:14AM
User who most recently changed record NTSB\MONR
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N66377
NTSB Number MIA99TA206
Missing Aircraft Indicator --
Federal Aviation Reg. Part Part 91: General Aviation
Type of Flight Plan filed None
Flight plan Was Activated? No
Damage Substantial
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name Hughes
Aircraft Model OH-6A
Aircraft Series Identifier --
Aircraft Serial Number 67-16571
Certified Max Gross Weight 2550
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 4
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection AAIP
Date of Last Inspection Jul 15 1999 12:00AM
Airframe hours since last inspection 10
Airframe Hours 2567
ELT Installed Yes
ELT Activated Yes
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name U.S. Border Patrol
Aircraft Owner Street Address 9C Butterfield Trail
Aircraft Owner City El Paso
Aircraft Owner State PR
Aircraft Owner Country USA
Aircraft Owner Zipcode 79906
Operator is an individual? No
Operator Name --
Operator Same as Owner? Yes
Operator Is Doing Business As --
Operator Address Same as Owner? No
Operator Street Address --
Operator City --
Operator State --
Operator Country --
Operator Zip code --
Operator Code --
Owner has at least one certificate None
Other Operator of large aircraft? --
Certified for Part 133 or 137 Operation --
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) Public Use
Second Pilot on Board No
Departure Point Same as Event Yes
Departure Airport Code BQN
Departure City --
Departure State --
Departure Country --
Departure Time --
Departure Time Zone AST
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 Emergency landing
Report sent to ICAO? No
Evacuation occurred No
Date of most recent change to record Feb 18 2004 3:11PM
User who most recently changed record KENJ
Since inspection or accident Time of Accident
Event Location Runway Number and Location NA
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --