Narrative: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: "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."
Loss of control
» National Interagency Fire Center
Follow-up / safety actions
Following the June 17 C-130A and July 18 PB4Y-2 Privateer airtanker accidents the Blue Ribbon Panel on Aerial Firefighting was commissioned by the Forest Service and the Bureau of Land Management. The panel was chartered to identify key information for planning the safe and effective future of aerial firefighting.
The report was released December 6, 2002 and revealed eight findings. As a result the Forest Service and the Bureau of Land Management decided no longer to contract for the C-130A or PB4Y aircraft as airtankers and the Forest Service suspended fire missions of 19 P-58 Barons and 4 Shorts 330 aircraft pending evaluations of the issues identified in the Blue Ribbon panel’s report.
The NTSB's investigation of three air tanker accidents determined that the maintenance and inspection programs applicable to firefighting aircraft did not adequately account for the increased safety risks that the aircraft are exposed to as a result of the advanced age and the severe stresses of the firefighting environment. As a result the NTSB recommended that the Department of Agriculture and the Department of Interior develop maintenance and inspection programs for firefighting aircraft that include consideration of the airplane's original design, age, and operational stresses, as well as engineering evaluations to predict and prevent fatigue cracking. The Board also recommended that the Department of Agriculture and Department of Interior hire personnel with aviation engineering and maintenance expertise to oversee the new maintenance programs. The NTSB recommended that the FAA require that these aircraft be maintained in accordance with such programs and that the FAA assume responsibility for collecting continuing airworthiness information about surplus military aircraft.
In a separate letter sent to the Department of Agriculture and the Department of Interior the Safety Board emphasized their position regarding the installation of video recorders on public use aircraft and.