Aloha Airlines Flight 243
Fuselage of Aloha Airlines Flight 243 after the explosive decompression.
|Date||28 April 1988|
|Summary||Explosive decompression caused by fatigue failure|
|Aircraft type||Boeing 737-297|
|Aircraft name||Queen Liliuokalani|
|Flight origin||Hilo Int'l Airport (ITO)|
|Destination||Honolulu Int'l Airport (HNL)|
Aloha Airlines Flight 243 (AQ 243, AAH 243) was a scheduled Aloha Airlines flight between Hilo and Honolulu in Hawaii. On April 28, 1988, a Boeing 737-297 serving the flight suffered extensive damage after an explosive decompression in flight, but was able to land safely at Kahului Airport on Maui. The only fatality was flight attendant Clarabelle "C.B." Lansing, who was blown out of the airplane. Another 65 passengers and crew were injured.
The safe landing of the aircraft despite the substantial damage inflicted by the decompression established Aloha Airlines Flight 243 as a significant event in the history of aviation, with far-reaching effects on aviation safety policies and procedures.
The flight departed Hilo at 13:25 with flight crew and 89 passengers. No unusual occurrences were noticed during the pre-departure inspection of the aircraft. The aircraft had previously completed 3 round-trip flights from Honolulu to Hilo, Maui, and Kauai. All flights were uneventful. Meteorological conditions were checked but no advisories for weather phenomenon occurred along the air route. see: Airman’s meteorological information (AIRMET) or significant meteorological information (SIGMET).
The aircraft, Queen Liliuokalani (registration number N73711, named after Lili'uokalani), took off from Hilo at 13:25 [Hawaii-Aleutian Standard Time|HST] on 28 April 1988, bound for Honolulu (PHNL). There were 89 passengers and 6 crew members on board. No unusual occurrences were reported during the take-off and ascent.
Around 13:48, as the aircraft reached its normal flight altitude of 24,000 feet (7,300 m) about 23 nautical miles (43 km) south-southeast of Kahului, Maui a small section on the left side of the roof ruptured with a "whooshing " sound. The captain felt the aircraft roll left and right, and the controls went loose. The First Officer noticed pieces of grey insulation floating over the cabin. The door to the cockpit was gone so the Captain could look behind him and see blue sky. The resulting explosive decompression tore off a large section of the roof, consisting of the entire top half of the aircraft skin extending from just behind the cockpit to the fore-wing area.
First officer Mimi Tompkins was flying the plane at the time of the accident. After discovering the damage, Captain Robert Schornstheimer took over and steered the plane to the closest airport at Maui island. 13 minutes later, the crew performed an emergency landing on Kahului Airport's runway 2. Upon landing, the crew deployed the aircraft's emergency evacuation slides and evacuated passengers from the aircraft quickly. Tompkins assisted passengers down the evacuation slide. In all, 65 people were reported injured, eight seriously. At the time, Maui had no plan for a disaster of this type. The injured were taken to the hospital by the tour vans from Akamai Tours (now defunct) driven by office personnel and mechanics, since the island only had a couple of ambulances. Air traffic control radioed Akamai and requested as many of their 15 passenger vans as they could spare to go to the airport (less than a mile away) to transport the injured. Two of the Akamai drivers were former medics and established a triage on the runway. The aircraft was a write-off.
Flight Attendant Clarabelle Lansing was the only fatality. She was a veteran flight attendant of 37 years at the time of the accident. Her body was never found. She had been at the 5th row and was swept out from the cabin.
A section from behind the cockpit was separated equal to one-fourth of the fuselage length. A flight attendant was killed and 7 serious injuries. All the passengers were in their seats and belted during depressurization. A major portion of the upper crown skin and structure of section 43 separated in flight causing an explosive decompression of the cabin. (See figure 1). Final damage consisted of the total loss of a major portion of the upper crown, and damage to other structure in section 43. Damage extended from the main entrance door, aft about 18 feet. The airplane was determined to be damaged beyond repair, and was dismantled on site.
After an extensive search of the ocean at the estimated coordinates where the accident took place, neither Lansing's body nor the piece of the fuselage that was blown off the plane was ever found. Investigation by the United States National Transportation Safety Board (NTSB) concluded that the accident was caused by metal fatigue exacerbated by crevice corrosion. The plane was 19 years old and operated in a coastal environment, with exposure to salt and humidity.
According to the official NTSB report of the investigation, Gayle Yamamoto, a passenger, noticed a crack in the fuselage upon boarding the aircraft prior to the ill-fated flight but did not notify anyone.
|This section does not cite any references or sources. (April 2013)|
In B 753, the fuselage is divided into four sections with sections 41, 43, 46, and 48. These sections along were met at butt joints. Disbonding of these bonds led to improper load distribution, and fatigue cracking. Additionally, the joint disbanding also led to corrosion which contributed to joint failure.
Multiple site damage was the main cause of the fuselage damage. MSD can range from a few fatigue cracks among many rivet holes to the worst case of small, visually undetectable fatigue cracks on both sides of rivet holes. Even though the small crack is not visualized it may lead to catastrophic destruction of the system. In the case of this 737 after the accident, a passenger reported that as she boarded, she noticed a large vertical fuselage crack, but didn’t mention it to anyone. This small crack propagated by MSD and the final analysis revealed that MSD was most prevalent in the mid-bay areas (between adjacent circumferential tear straps). A fatigue crack up to 0.52 inches in length was evident in lap joints along s “10L” near body STA 520 (near the missing area). A section of S4R is found out from the right wing which contained many cracked portions that originated due to disbanding of cold bonded lap joints and hot bonded tear joints. Due to this, the function of the joint is lost and the rivets start to carry the loads. When a rivet hole is stressed, a knife-edged crack starts to form. The analysis shows that it is probable that a large number of small cracks at the S-10L may have joined to form a large crack. With the data obtained from damage due to accident, theoretical calculations on crack interaction, MSD propagation rate, and the service history of B-737 lap joint disbonded problems, the safety Board concluded that, at the time of the accident, numerous fatigue cracks in the fuselage skin lap joint along S-10L linked up quickly to cause catastrophic failure of a large section of the fuselage.
For the production line number 291 (B-737), the outer layer was not there—it was milled away. In the case of production line 292 and after, this outer line was kept there to give an additional thickness of .036 inch at the joint (fig 3,). In airplane line number 291 and before they utilized cold bonding, with fasteners used to maintain surface contact in the joint, allowing bonding adhesive to carry/transfer load between skin panels. This cold bonded joint uses an epoxy impregnated woven scrim cloth to join the edges of .036 inch skin panels and also this epoxy cloths are reactive at room temperature. For that reason it was stored in dry ice temperatures only. This bond cured at room temperature after assembly. Cold bonding process can reduce the overall weight and manufacturing cost. Fuselage hoop loads (circumferential pressurization loads) were intended to be transferred through the bonded joint, rather than through the rivets, allowing the use of lighter, thinner fuselage skin panels with no degradation in fatigue life. This construction improved the known problems with the joint by: • Eliminating the knife-edge fatigue detail, which resulted from the countersunk rivets in a disbonded upper skin • Eliminating the corrosion concern associated with the scrim cloth, which could wick moisture into the lap joint 
Pressure vessel engineer Matt Austin has proposed an alternative hypothesis to explain the disintegration of the fuselage of Flight 243. This explanation postulates that initially the fuselage failed as intended and opened a ten-inch square vent. As the cabin air escaped at over 700 mph, flight attendant C.B. Lansing became wedged in the vent instead of being immediately thrown clear of the aircraft. The blockage would have immediately created a pressure spike in the escaping air, a fluid hammer (or "water hammer"), which tore the jet apart. The NTSB recognizes this hypothesis, but the board does not share the conclusion and maintains its original finding that the fuselage failed at multiple points at once. Former NTSB investigator Brian Richardson, who led the NTSB study of Flight 243, believes the fluid hammer explanation deserves further study.
The investigation determined that weather had no role in this accident. The quality of inspection and maintenance programs were deficient. Also, the fuselage failure initiated in the lap joint along S-10L; the failure mechanism was a result of multiple site fatigue cracking of the skin adjacent to rivet holes along the lap joint upper rivet row and tear strap disbond which negated the fail-safe characteristics of the fuselage. Finally, the fatigue cracking initiated from the knife edge associated with the countersunk lap joint rivet holes; the knife edge concentrated stresses that were transferred through the rivets because of lap joint disbonding.
- Miracle Landing
- Uncontrolled decompression
- List of notable decompression accidents and incidents
- List of accidents and incidents on commercial airliners
- Air safety
- China Airlines Flight 611
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