Preliminary flight loads analysis of MD-87 as a heavy airtanker

Abstract

Results of analyzing in-flight recorded data from a fleet of five MD-87 airtankers flown in support of the United States Forest Service aerial firefighting operations are reported. Data has been available from two different flight data recorders, allowing comparison of their results. Missions have been placed in three categories of firefighting, ferry, and maintenance/training. Firefighting missions have been further divided into five distinct flight phases. Flight loads due to gusts and maneuvers have been separated using the two-second rule. Method of peaks-between-means has been used to for establishing flight loads exceedance spectra and the results are shown for each flight phase. The gust load factor spectra are shown to be similar to those of other USFS aircraft flown in the same environment. The maneuver load factor spectra are shown to indicate smaller loads than those of legacy airtankers, but considerably more frequent than those of civil transport.