Operational Assessment of Heavy Air Tankers

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Operational Assessment of Heavy Air Tankers

Rokhsaz, Kamran / Kliment, Linda K. / Nelson, John / Newcomb, James

Flight data collected by various P2V and P3A air tankers in actual operation over several seasons have been used to construct statistical information on aircraft usage and maneuver load spectra in this role. The data used for this report consist of 5316 flight files, collected during the 2008 and 2009 fire seasons. Flights have been divided into multiple phases, separating the segments when retardant is dropped from others. Basic flight parameters such as airspeed, altitude, flight duration and distance, bank, and pitch angles are shown in statistical form. Vertical accelerations are used to construct $V - n$ diagrams for comparison with the manufacturers’ data. Airframe cycle times are shown to be approximately 45 min. Several coincident flight events are shown and compared with operational limits when available. The altitudes, the normal accelerations, and the airspeeds have not revealed any operation outside of the established boundaries. Relatively large dive and roll angles were prominently present during all but the drop phases. Nonetheless, they are shown to remain within the limits stated by the manufacturer or imposed by the Federal Aviation Administration type certificate data sheets. Cumulative occurrences of maneuver loads have been examined and compared with data from other sources when available. It is shown that the cumulative occurrences of maneuver load factor varies by flight phase, with the largest values associated with the drop and exit phases. For the overall flight, maneuver loads were shown to occur at lower frequencies than those stated in Military specification MIL-A-8866C(AS).