Consolidated-Vultee P4Y-2 N7620C

Summary

On 19 July 2002 at about 00:40 local time, a Consolidated-Vultee P4Y-2 registered N7620C was involved in an accident near Estes Park, Colorado, United States. 2 people were on board and 2 died. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

19 July 2002 at 00:40

Classification

Accident

Location

Estes Park, Colorado, United States

Coordinates

40.3128, -105.2369

Aircraft

Consolidated-Vultee P4Y-2

Registration

N7620C

Category

Airplane

Engines

4

Operator

Not recorded

Operating rule

Public Use

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Broomfield → Unknown

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

DEN02GA074

2 people died.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.