Southwest Airlines Flight 812 Case Study

The failure of the fuselage along a lap joint due to metal fatigue has caused Southwest Airlines Flight 812 to suffer a rapid decompression mid-flight. The investigation has revealed that the failure was due to cracks found in the aluminum skin of the fuselage [1]. The rupture is shown in figure 1 below. Boeing had predicted that such cracks found in the aircraft would not result in failure at such an early stage [2]. While most aircrafts are still considered to be safe for flight even when they have cracks in their structures, as long as the relevant parts are fixed or replaced before ultimate failure [3]. However, it is disconcerting to know that some cracks may go undetected and eventually cause failure. Such a failure can be and should

One of the most significant predecessor was the Aloha Airlines Flight 243 on 28th April 1988. Metal fatigue on the Boeing 737-297 led to a hole that spanned about a third of the fuselage’s roof; it resulted in a rapid decompression that sucked a flight attendant, Clarabelle Lansing, out of the aircraft [11] [12]. Another incident of metal fatigue that has led to a rupture was in October 2010 on American Airlines Flight 1640. A 1-foot by 2-foot hole was found on the roof of the Boeing 757 aircraft. Flight 1640 had to make and emergency landing due to decompression and thankfully, no one was hurt [13].

These events show that metal fatigue has plagued the aviation industry for a long time and still continues to occur. Yet, we carry on using the same old methods to approach such problem that has clearly proven ineffective. There has been no new solution formulated to ensure that such a failure can be fully prevented. 3. Material

The graph has 3 main regions. The first region (Stage I) is where the crack starts to form slowly, ΔK is relatively small and the gradient increases positively at a slow rate. The second region (Stage II) is where the crack growth is at right angles to the maximum tensile stress and fatigue striations are formed. This region is also dubbed the “power law region” as the crack grows at a constant rate m and ΔK increases constantly too. The last region is where the crack growth rate is exponential as the crack size is close to the critical crack length and crack growth is unsteady, and ΔK is close to