Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Bennett, Colorado 80011
Wednesday, May 1, 1991 6:53 MDT
NTSB Narrative Summary Released at Completion of Accident
SHORTLY AFTER TAKEOFF, WHILE CLIMBING TO CRUISE ALTITUDE, THE PILOT REPORTED THE LEFT ENGINE COWL ASSEMBLY HAD COME OFF. WITNESSES OBSERVED THE AIRPLANE AT LOW ALTITUDE & NOTED THAT IT WAS 'YAWING, SPUTTERING, AND ROCKING BACK AND FORTH.' THEY INDICATED THE LEFT ENGINE WAS NOT RUNNING & THAT THE AIRPLANE BANKED SHARPLY TO THE RIGHT & DISAPPEARED BEHIND TREES BEFORE CRASHING. AN INVESTIGATION REVEALED THE LEFT PROPELLER HAD NOT BEEN FEATHERED. THE LEFT ENGINE COWLING WAS FOUND 1.8 MILES FROM THE ACCIDENT SITE. THE THREE PRIMARY (EYEBOLT) COWL FASTERERS ON THE OUTBOARD SIDE OF THE LEFT UPPER COWL WERE FOUND UNLOCKED & SEVEN OTHER COWL ATTACHING STUDS (SCREWS) WERE MISSING. THE COWLING HAD BEEN REMOVED 16 DAYS BEFORE THE ACCIDENT TO INSTALL AN OIL/AIR SEPARATOR. THIS WAS THE FIRST FLIGHT SINCE THAT WORK WAS PERFORMED. THE MECHANIC, WHO DID THE WORK, SAID HE NOTED SEVERAL COWL STUD FASTENERS WERE MISSING & THAT HE HAD NOTIFIED THE PILOT. THE PILOT WAS REPORTED TO HAVE REPLIED THAT HE HAD SOME FASTENERS & WOULD TAKE CARE OF THE PROBLEM.
NTSB Probable Cause Narrative
IN-FLIGHT SEPARATION OF THE LEFT ENGINE COWL ASSEMBLY THAT WAS NOT PROPERLY LATCHED, AND FAILURE OF THE PILOT TO MAINTAIN MINIMUM CONTROL SPEED, WHICH RESULTED IN HIS LOSS OF AIRCRAFT CONTROL. FACTORS RELATED TO THE ACCIDENT WERE: AN INADEQUATE PREFLIGHT INSPECTION, INADEQUATE MARKINGS/ALIGNMENT INDICATIONS TO ASSURE THAT THE COWL FASTENERS WERE LOCKED, AND AN INSUFFICIENTLY DEFINED PROCEDURE IN THE FLIGHT MANUAL FOR CHECKING THE COWL FASTENERS.
Event Information
| Type of Event | Accident |
| Event Date | 5/1/1991 |
| Event Day of the Week | Wednesday |
| Time of Event | 653 |
| Event Time Zone | Mountain Daylight Time |
| Event City | BENNETT |
| Event State | COLORADO |
| Event Country | -- |
| Zipcode of the event site | 80011 |
| Event Date Year | 1991 |
| Event Date Month | 5 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| Event Location Airport | |
| 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 | 0 |
| Degrees magnetic from airport | 0 |
| Airport Elevation | 0 |
| Weather Briefing Completeness | Unknown |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 657 Mountain Daylight Time |
| Direction of event from weather observation facility (degrees) | 240 |
| Weather Observation Facility ID | APA |
| Elevation of weather observation facility | 5883 |
| Distance of event from weather observation facility (units?) | 21 |
| Time Zone of the weather observation | MDT |
| 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) | 50 |
| Air Temperature at event time (in degrees celsius) | -18 |
| Dew Point at event time (in degress fahrenheit) | -18 |
| Wind Direction (degrees magnetic) | 150 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 3 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Unknown |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | -- |
| Density Altitude (feet) | 0 |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | Fatal |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | 1 |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 1 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 2008 |
| NTSB Notification Source | -- |
| NTSB Notification Date | May 1 1991 12:00AM |
| NTSB Notification Time | 700 |
| Fiche Number and/or location -used to find docket information | 44985 |
| Date of most recent change to record | Dec 18 2002 11:28AM |
| User who most recently changed record | NTSB\GIUV |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N7407L |
| NTSB Number | DEN91FA065 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 91: General Aviation |
| Type of Flight Plan filed | None |
| Flight plan Was Activated? | -- |
| Damage | Destroyed |
| Aircraft Fire | Ground |
| Aircraft Explosion | Ground |
| Aircraft Manufacturer's Full Name | PIPER |
| Aircraft Model | PA-31B-310 |
| Aircraft Series Identifier | PA-31B-310 |
| Aircraft Serial Number | 31-790 |
| Certified Max Gross Weight | 6500 |
| Aircraft Category | Airplane |
| 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 | 6 |
| Number of Engines | 2 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Unknown |
| Date of Last Inspection | -- |
| Airframe hours since last inspection | 0 |
| Airframe Hours | -- |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | |
| Aircraft Owner Street Address | |
| Aircraft Owner City | |
| Aircraft Owner State | |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | |
| Operator is an individual? | -- |
| Operator Name | JOHN WESTBROOK |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | 7395 S. PEORIA ST, HANGAR 8 |
| Operator City | ENGLEWOOD |
| Operator State | CO |
| Operator Country | |
| Operator Zip code | 80112 |
| 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) | Business |
| Second Pilot on Board | No |
| Departure Point Same as Event | No |
| Departure Airport Code | APA |
| Departure City | ENGLEWOOD |
| Departure State | CO |
| Departure Country | |
| Departure Time | 645 |
| Departure Time Zone | MDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | DSM |
| Destination City | DES MOINES |
| Destination State | IA |
| Destination Country | |
| Specific Phase of Flight | Descent |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 2 2001 10:35AM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 0 |
| Runway Length | 0 |
| Runway Width | 0 |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |