20 Years ago today: On 18 July 2002 a Hawkins & Powers Aviation Consolidated PB4Y-2 Super Privateer crashed after suffering an inflight failure of the left wing due to fatigue cracking, killing both pilots.

Date:Thursday 18 July 2002
Time:18:40 MDT
Type:Silhouette image of generic P4Y model; specific model in this crash may look slightly different
Consolidated PB4Y-2 Super Privateer
Operator:Hawkins & Powers Aviation
First flight:1945
Total airframe hrs:8346
Engines:Wright R-2600-35
Crew:Fatalities: 2 / Occupants: 2
Passengers:Fatalities: 0 / Occupants: 0
Total:Fatalities: 2 / Occupants: 2
Aircraft damage:Destroyed
Aircraft fate:Written off (damaged beyond repair)
Location:10 km (6.3 mls) SW of Estes Park, CO (https://cdn.aviation-safety.net/database/country/flags_15/N.gif   United States of America)
Phase:Maneuvering (MNV)
Nature:Fire fighting
Departure airport:Broomfield-Jeffco Airport, CO (BJC/KBJC), United States of America
Destination airport:Broomfield-Jeffco Airport, CO (BJC/KBJC), United States of America

Super Privateer ‘Tanker 123’ was being used by the U. S. Department of Agriculture Forest Service to drop fire retardant on the Big Elk fire near Lyons, CO. The airplane was loaded with approximately 2,000 gallons of fire retardant, and 550 gallons of fuel and departed Broomfield-Jeffco Airport at 18:15.
The crew of a DC-4 (‘Tanker 161’) saw Tanker 123 in a base turn for the drop and in a “smooth 15 to 20 degree bank turn,” when the left wing separated from the airplane inboard of the number 2 engine. The aircraft pitched nose down in a huge fireball and plunged into the ground vertically starting an immediate large fire. The investigations into the June 17, 2002 C-130A and July 18 P-4Y crashes are closely looking at the fatigue cracks as well as other safety issues, such as inspection and maintenance procedures and operational factors. Preliminary results for both have indicated that widespread fatigue was not evident over the entire wing but that in some locations current crack detection techniques may have been unreliable.
Probable Cause:

PROBABLE CAUSE: “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.”