On December 19, 2005, Flying Boat, Inc. dba as Chalk’s Ocean Airways, flight 101, a Grumman Turbo Mallard (G-73T) amphibious airplane, registration number N2969, crashed off Port of Miami, Florida. The Mallard, a regularly scheduled flight to Bimini, Bahamas, had taken off moments before from the Miami Seaplane Base; the right wing departed the aircraft during climb and the Mallard plunged back into the Atlantic Ocean.
The root cause of the accident was corrosion that weakened the wing structure, in this case the right wing. The flexing of the wings during flight operations; the loads placed on the wings and the weakening of the aircraft’s integrity by corrosion eventually overwhelmed the wing’s structural strength; the wing catastrophically separated from the aircraft.
The aircraft, fifty-eight-years old at the time, was operated in a most hostile of aviation environments: saltwater and considerable humidity. The airplane was not just operated near saltwater, it was operated in saltwater. Because of this metal hazardous environment, corrosion was always a threat to the structure and the engines. Any gaps in the skin or moving components, e.g. flight controls, were susceptible; the two detrimental agents: salt and water, would easily hide within the crevasses and joints of aircraft components and require regular evacuating.
The National Transportation Safety Board (NTSB) as part of the accident investigation, focused attention on the Flying Boat, Inc.’s continuous airworthiness maintenance program (CAMP) and continuing analysis and surveillance system (CASS). Per accident report AAR-07/04, “As part of its CAMP and CASS program, Chalk’s Ocean Airways was required to monitor the mechanical performance of the flying fleet by collecting and analyzing data.” The CASS program was part of the CAMP and was dependent on the quality of data provided; the CASS was useless if the data was less than adequate or corrupted.
The concept of maintenance programs as they are today was born of the maintenance steering group (MSG) program. As per skybrary.aero, “… ‘Operator/Manufacturer Scheduled Maintenance Development’ is a document … The main idea behind this concept is to recognize the inherent reliability of aircraft systems and components …” MSG-1 was organized in 1968 for the B747s; MSG-2 was developed for scheduled maintenance for 1970s vintage aircraft and MSG-3 was first published in 1980; MSG-3 focused on ‘consequences of failure’.
The exact dates of the MSG were not important except to show when the programs came about. The aircraft designed and built before MSG-1 were not required to be included in the MSG retroactively; they were required, as part of their certification, to have a maintenance program built that would capture necessary maintenance requirements.
The accident aircraft, registration number N2969, was manufactured in May 1947. As part of its certification requirements, Flying Boat Inc.’s CAMP was developed; that included the CASS. In addition, Flying Boat was required per Title 14 Code of Federal Regulations (CFR) Part 121.1105 (December 2002) to have an Aging Airplane Inspections and Records Review (AAIRR). Part121.1105 applied to “… all airplanes operated by a certificate holder under this part  …” Per paragraph (b)(1), the operator could not operate an airplane unless they had an aging aircraft inspection and records review for, “Airplanes exceeding 24 years … not to exceed 7 years.” Operators, such as Flying Boat, had to prove “that the maintenance of age-sensitive parts and components of the airplane has been adequate and timely enough to ensure the highest degree of safety.” The review was completed in October 2005.
Why did the review miss what led to flight 101’s accident? On July 18, 2002, a Consolidated-Vultee P4Y-2 crashed in Estes Park, Colorado (accident number DEN02GA074). The aircraft, operating as a fire fighter, suffered a left-wing separation during a ‘drop’ maneuver. The aircraft impacted terrain. The P4Y-2 was manufactured as a bomber in 1944 during World War II.
One of the findings I made investigating this accident and another involving a C130A in California two months earlier (accident number LAX02GA201) with a dual wing separation, was that the operator of both aircraft, Hawkins and Powers (H&P), had CAMP and CASS-type programs designed for their P4Y-2, C130 and other models in their fleet. In conversation with the H&P chief inspector, it was learned that the fleet did not have a corrosion prevention and control program (CPCP) as part of their maintenance program.
November 29, 1993, the Federal Aviation Administration (FAA) issued Order 8300.12, Corrosion Prevention and Control Programs. The corrosion programs were dependent on the requirements of the manufacturer’s Baseline Program. The CPCPs were aimed at commercial aircraft whose age was substantial, e.g. B727, DC-8 and BAC1-11. Using the manufacturer’s baseline, operators of older aircraft could have used the manufacturer’s program or generate one acceptable to the FAA and the manufacturer.
The CPCP program, as described in FAA Order 8300.12, was a comprehensive and effective program that could have been designed to meet the needs of any aircraft built before the required date. The Order spelled out how the program worked, was revised and the recording of data. The surveillance of the program included actions required at different corrosion levels. This would have given the FAA Principle Maintenance Inspector for Flying Boats, Inc. a blueprint to approve a successful program. Per AAR-07/04, Flying Boats, Inc. did not have a CPCP for the Mallard fleet.
Consolidated-Vultee, manufacturer of the H&P’s P4Y-2, was no longer in business. Furthermore, the P4Y-2 was not required to follow FAA Order 8300.12 due to its age. However, at the time, it was the failure of H&P to have a CPCP in place that allowed, among other things, for the aircrafts’ corrosion and structural degradations to go unnoticed. In the G-73T Mallard’s case, corrosion had infiltrated the wing structure and fuselage so severely it was difficult to determine where metal began, and sealant ended. The wings suffered from many types of corrosion effects, e.g. crevice or environmental cracking. N2969 and her sister aircraft, were flying on borrowed time.
The CPCP, AAIRR, CAMP or other acronym and alphabet programs did not fail to capture the data; the FAA did not miss the signs; the NTSB did not fail to pass on what it knew. What destroyed the Mallard and the two H&P planes was a lack of common sense; this was the root cause of all these accidents. Grumman never expected that the G-73T would have as long a life as it did, operated as a regularly scheduled airliner into the next century. Consolidated-Vultee never designed the P4Y-2 to fly through mountain passes. It was a bomber; it was not designed for the incredible stresses of a firefighter.
As early as 1988, aircraft manufacturers were handed a cold plate of reality when Aloha Airlines flight 243 nearly came apart in flight. Flight hours, how many hours an aircraft spent flying, long thought to be the standard of measure of an aircraft’s lifespan, would need to be replaced with a more telling measure: flight cycles, which measured how many times a plane took off/landed. Aloha 243 was the catalyst to limiting commercial airliner lifetimes. Common sense won out.
Flying Boats, Inc. operated outside the norm as did H&P. The industry gave little thought to flying boats; there were bigger airplanes to worry about. Manufacturers saw no money in designing amphibious 18-seated airplanes or firefighters. Common sense had no means to cultivate in an industry that took no notice. Meanwhile, Mother Nature, often thought by the arrogant to be placed under control, will always play the last card.