Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Estes Park, Colorado 80517
Thursday, July 18, 2002 18:40 MDT
NTSB Narrative Summary Released at Completion of Accident
The airplane was maneuvering to deliver fire retardant when its left wing separated. Aircraft control was lost and the airplane crashed into mountainous terrain. A witness on the ground took a series of photographs that showed the airtanker's left wing separating at the wing root and the remaining airplane entering a 45-degree dive to the ground in a counterclockwise roll. An examination of the airplane wreckage revealed extensive areas of preexisting fatigue in the left wing's forward spar lower spar cap, the adjacent spar web, and the adjacent area of the lower wing skin. The portion of the wing containing the fatigue crack was obscured by the retardant tanks and would not have been detectable by an exterior visual inspection. An examination of two other airtankers of the same make and model revealed the area where the failure occurred on the accident airplane was in a location masked by the airplane's fuselage construction. The airplane was manufactured in 1945 and was in military service until 1956. It was not designed with the intention of operating as a firefighting airplane. In 1958, the airplane was converted to civilian use as an airtanker and served in that capacity until the time of the accident. The investigation revealed that the owner developed service and inspection procedures for the airtanker; however, the information contained in the procedures did not adequately describe where and how to inspect for critical fatigue cracks. The procedures were based on U.S Navy PB4Y-2 airplane structural repair manuals that had not been revised since 1948.
NTSB Probable Cause Narrative
the inflight failure of the left wing due to fatigue cracking in the left wing's forward spar and wing skin. A factor contributing to the accident was inadequate maintenance procedures to detect fatigue cracking.
Event Information
| Type of Event | Accident |
| Event Date | 7/18/2002 |
| Event Day of the Week | Thursday |
| Time of Event | 1840 |
| Event Time Zone | Mountain Daylight Time |
| Event City | Estes Park |
| Event State | COLORADO |
| Event Country | -- |
| Zipcode of the event site | 80517 |
| Event Date Year | 2002 |
| Event Date Month | 7 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 401846N |
| Event Location Longitude | 1051413W |
| 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 | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | Not pertinent |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1858 Mountain Daylight Time |
| Direction of event from weather observation facility (degrees) | 145 |
| Weather Observation Facility ID | BJC |
| Elevation of weather observation facility | 5670 |
| Distance of event from weather observation facility (units?) | 27 |
| Time Zone of the weather observation | MDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 12000 |
| Lowest Non-Ceiling Height | 8000 |
| Sky/Lowest/Cloud Conditions | Few |
| Sky Condition for Lowest Ceiling | Broken |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 30 |
| Air Temperature at event time (in degrees celsius) | 34 |
| Dew Point at event time (in degress fahrenheit) | 11 |
| Wind Direction (degrees magnetic) | 40 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 8 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 30.04 |
| Density Altitude (feet) | 9146 |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | Fatal |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | 2 |
| Injury Total Minor | -- |
| Injury Total None | -- |
| Injury Total Serious | -- |
| Injury Total All | 2 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 13174 |
| NTSB Notification Source | FAA COMM CTR |
| NTSB Notification Date | Jul 18 2002 12:00AM |
| NTSB Notification Time | 1905 |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Jul 23 2003 8:35AM |
| User who most recently changed record | NTSB\MONR |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | Denver, Colorado FSDO |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N7620C |
| NTSB Number | DEN02GA074 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Public Use |
| Type of Flight Plan filed | Company VFR |
| Flight plan Was Activated? | Yes |
| Damage | Destroyed |
| Aircraft Fire | Ground and In-flight |
| Aircraft Explosion | Ground and In-flight |
| Aircraft Manufacturer's Full Name | Consolidated-Vultee |
| Aircraft Model | P4Y-2 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 66260 |
| Certified Max Gross Weight | 69990 |
| 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 | 3 |
| Number of Engines | 4 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Continuous Airworthiness |
| Date of Last Inspection | Jun 14 2002 12:00AM |
| Airframe hours since last inspection | 87.29 |
| Airframe Hours | 8346.3 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | Hawkins & Powers Aviation, Inc. |
| Aircraft Owner Street Address | P. O. Box 391 |
| Aircraft Owner City | Greybull |
| Aircraft Owner State | WY |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 82426 |
| Operator is an individual? | No |
| Operator Name | -- |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | -- |
| Operator City | -- |
| Operator State | -- |
| Operator Country | -- |
| Operator Zip code | -- |
| Operator Code | -- |
| Owner has at least one certificate | -- |
| Other Operator of large aircraft? | -- |
| Certified for Part 133 or 137 Operation | Agriculture |
| 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) | Aerial Application |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | BJC |
| Departure City | Broomfield |
| Departure State | CO |
| Departure Country | USA |
| Departure Time | 1814 |
| Departure Time Zone | MDT |
| 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 | Maneuvering - aerial application |
| Report sent to ICAO? | No |
| Evacuation occurred | No |
| Date of most recent change to record | Feb 25 2003 11:51AM |
| User who most recently changed record | MCBM |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | -- |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |