MIAMI – On April 28, 1988, Aloha Airlines (AQ) flight 243 suffered an explosive decompression, leaving a dead flight attendant and issues related with inspection and maintenance programs.
During the explosion, the ceiling of the Boeing 737-200 was torn open, but the Captain was able to land the damaged jet with 65 passengers and crew on board. The jettisoned flight attendant was never found.
Prior to the flight from Hilo for Honolulu, the Boeing 737-200 aircraft underwent a normal walkaround pre-flight inspection by the first officer who did not find anything unusual. At 13:25, flight 243 departed for the capital that it would never reach on that day.
When the airplane climbed to 24,000 feet, an explosive decompression took place. At that moment, the roof flew out from the aircraft and the 58-year-old flight attendant, Clarabelle Lansing, who was in row 5, was ejected into the void.
Co-pilot Tompkins was flying the aircraft when the incident occurred; 44-year-old Captain Robert Schornstheimer took over and steered the aircraft to begin an emergency descent to Maui, managing to land the aircraft safely without taking any more lives.
In addition to the flight attendant fatallity, seven passengers and another flight attendant had serious injuries.
At the time of the incident, the Boeing 737-200 had accumulated 89,680 flight-cycles and 35,496 flight-hours. It was later known that just before departure, a damage in the aircraft was reported by a passenger who did not mention it to the crew.
The anomaly was a longitudinal fuselage crack, which after checks turned out to be a fissure in the upper row of rivets along the stringer S-10L lap joint. The approximate location of the failure was located between the cabin door and the jet bridge hood.
The Boeing 737-200 was damaged beyond repair and was dismantled on site. Additional damage to the airplane included damaged and dented horizontal stabilizers, both of which had been struck by flying debris.
Further investigations disclosed that the primary damage was caused by the total separation of the upper crown skin and other fuselage structure. The failure extended from the small aft of the main cabin to the entrance door aft, running 18 feet, according to videos taken during and after the landing.
Due to the findings, the National Transportation Safety Board (NTSB) determined that the failure of the AQ maintenance program to detect the presence of significant disbonding and fatigue damage was the probable cause of the accident.
As fuselage examinations were scheduled during the night, this made it more difficult to carry out an adequate inspection of the aircraft’s outer skin.
AQ maintenance program
By that time, the airline used a maintenance program based on a D-check (heavy maintenance and inspection check) interval of 15,000 flight-hours, according to Federal Aviation Administration (FAA). In contrast, a the time of the incident, Boeing recommended a 20,000 flight-hour interval.
While the Boeing’s Maintenance Planning Document proposed a D-check in a aircraft during few weeks apart, AQ separated the check into 52 separate work packages. Parts of D-check items were included in the overnight B-checks.
Regarding these procedurals, the NTSB stated that this practice was inappropriate to assess the overall condition of an airplane, outlining “the maintenance and inspection personnel that each airplane would need to have fully operational status to meet the next day’s flying schedule.”
As AQ had unusually short flights in its schedule, flight-cycles doubled the accumulated the rate that Boeing considered in its maintenance recommendations.
Consequently, the accumulation of flight-cycles produced the initiation of fatigue cracks and the following rate of crack growth in pressurized fuselage structure; as a result, the damage was not caused by the quantity of flight-hours.
Aircraft maintenance legacy
Back in the 80s, these circumstances were not sufficiently regarded during the release of the AQ maintenance program and its approval by the FAA.
The NTSB concluded in its final report on the accident:
“The National Transportation Safety Board determines that the probable cause of this accident was the failure of the Aloha Airlines maintenance program to detect the presence of significant disbonding and fatigue damage which ultimately led to failure of the lap joint at S-10L and the separation of the fuselage upper lobe.”
“Contributing to the accident were the failure of Aloha Airlines management to supervise properly its maintenance force; the failure of the FAA to require Airworthiness Directive 87-21-08 inspection of all the lap joints proposed by Boeing Alert Service Bulletin SB 737-53A1039; and the lack of a complete terminating action (neither generated by Boeing nor required by the FAA) after the discovery of early production difficulties in the B-737 cold bond lap joint which resulted in low bond durability, corrosion, and premature fatigue cracking.”
The safe landing of the at Maui established the incident as a significant event in the history of aviation, with far-reaching effects on aviation safety policies and procedures for year to come.