2. Small aircraft fatigue
Like any aircraft, the LSA are subjected to a wide spectrum of operational loads. The level of allowed acceleration for the LSA is higher than for the planes of transport category: the maximum positive load factor prescribed, for example for the Viper SD-4 [3] is equal to +4.0g, the minimum is – 2.0g.
As a proof of the necessity of the special attention to the metal fatigue for small aircraft the fatigue damage case study of the Piper aeroplane primary structure may be considered. During a routine inspection of a Piper Model PA-46-350P aeroplane, 1.53-inch () fatigue crack was discovered in the main spar lower cap (Fig.1). The crack discovery was at 5,273-hour time-in-service (TIS) versus the type certificated life limit of 15,580 hours TIS [4].
The list of fatigue issues could be extended, but even these examples prove the requirements for the special attention for the aircraft primary structure fatigue.