2002 Airtanker Crashes - P4Y-2, N7520C, Estes Park, Colorado

P4Y-2, N7520C, Estes Park, Colorado

The second crash occurred on July 18, 2002 near Estes Park, Colorado, also as a result of structural failure, in this case in the wing's spar adjacent to the left side of the fuselage. The aircraft, "Tanker 123", was loaded with 2,000 US gallons (7,600 L) of retardant. At the time of the accident, it was in a left turn from downwind to final approach for its eighth drop of the day on the Big Elk fire. While still in the 15°-20° left bank, witnesses on the ground and in another tanker observed the left wing separate from the aircraft and "fold upwards", followed almost immediately by the initiation of a fire. The aircraft continued to roll left, impacting the ground at a 45° nose down attitude, starting a large fire at the wreck site. Both crewmen were killed in the crash.

The aircraft, a Consolidated-Vultee PB4Y-2 Privateer, BuNo 66260, (the designation was later changed by the Navy to P4Y-2), was a variant of the World War II B-24 Liberator. It had been delivered in July, 1945 to the U.S. Navy who used it for coastal patrol duties. In 1952, it was transferred to the U.S. Coast Guard, who flew it until it was retired in 1956. The aircraft was pulled out of storage and converted to an airtanker in 1958, and was flown by several different companies, the last being Hawkins & Powers. At the time of the crash, the airframe had logged 8,346.3 flight hours.

A detailed investigation by the NTSB showed that the wing's lower spar cap had extensive stress fatigue and had fractures through the lower spar cap, vertically up the spar web and into the upper spar cap. The lower wing skin also found signs of fatigue in the area adjacent to the cracked spar cap. An examination of two other similar aircraft showed that the area of cracking was hidden from view by other fuselage structure.