Operational data recorded from five agricultural aircraft are used to compare their flight loads. Four of the airframes were used as single-engine air tankers, while the fifth was flown exclusively for agricultural applications. The data collectively consisted of 454 hours of flight time from firefighting and 100 hours from the agricultural operation. Gust and maneuver vertical load factors are separated using the two-second rule and their cumulative occurrences are presented per 1000 hours. The flight loads spectra are presented for the overall flight, and for individual phases. Gust loads are shown to behave similarly for all missions. Air tankers are shown to be subject to a large load factor during the drop phase, which occurs once or twice per flight. In the case of agricultural missions, the positive load factors do not reach very high values, but occur at much larger frequencies. It is also shown that the load factor alone is not a sufficient indicator of the stresses exerted on the structure due to the large changes in the aircraft weight.
展开▼
