The National Transportation Safety Board today issued recommendation letters to the Department of Agriculture, the Department of Interior and to the Federal Aviation Administration regarding maintenance programs for aircraft used in fire fighting operations.
The recommendations are part of a package that includes probable causes for three air tanker accidents caused by in-flight wing separations resulting from fatigue fractures. The three accidents are a June 17, 2002 crash of a C-130 in Walker, California (LAX02GA201); the July 18, 2002 crash of a P4Y-2 in Estes Park, Colorado (DEN02GA074); and a revised narrative and probable cause for the August 13, 1994 crash of a C-130 in Pearblossom, California (LAX94FA323). All three aircraft were involved in firefighting operations at the time of the accident. Fatigue cracking was cited as the probable cause for all three accidents, with inadequate fatigue detection procedures cited as a factor in each.
"We hope the release of these reports will raise operator awareness of the unique problems that affect these specialized aircraft, and the importance of a thorough maintenance program to detect safety issues and prevent accidents," said NTSB Chairman Ellen Engleman-Conners.
The Board's investigation of these accidents determined that the maintenance and inspection programs currently applicable to firefighting aircraft do 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. Firefighting flights conducted on behalf of the U.S. Government are public operations and are not required to comply with many of the federal aviation regulations (FARs). However, many of the maintenance provisions in the FARs do not address the unique safety risks of firefighting aircraft.
As a result the Board recommends 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 recommends that the Department of Agriculture and Department of Interior hire personnel with aviation engineering and maintenance expertise to oversee the new maintenance programs.
Along with recommendations for more rigorous maintenance programs for firefighting aircraft, the Board recommends that the FAA require that restricted-category aircraft used in firefighting operations be maintained in accordance with such programs. The Safety Board further recommends that the FAA assume responsibility for collecting continuing airworthiness information about surplus military aircraft from the organization that last provided technical or engineering support for an 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 encouraging the agencies to do so without delay.
The initial investigation of the Pearblossom accident in 1994 resulted in a different probable cause. However a recent review of the accident information, including the examination of wreckage that was not recovered in the initial investigation, revealed previously undiscovered evidence of fatigue fracturing in right-side, center-wing fragments that supported revising the probable cause.
The complete report briefs and the recommendation letters are available on the NTSB website, www.ntsb.gov.