HH-60G Airframe Service Life via Multi-Element Damage Monte Carlo Risk Analysis

The United States Air Force (USAF) HH-60G Pave Hawk helicopter did not have a defined structural service life since it was originally designed for crash-survivability and economic replacement of all critical parts. To quantify the service life of HH-60G due to the onset of Widespread Fatigue Damage (WFD), the Mercer Engineering Research Center (MERC) created new Multi-Element Damage (MED) Monte Carlo risk analysis methods that utilize the available data provided by the HH-60G's Aircraft Structural Integrity Program (ASIP). The Single Flight Probability of Failure (SFPOF) calculated by the Monte Carlo programs show that the current maintenance strategy of annual visual inspections is not sufficient to reach a 20,000 Equivalent Flight Hour (EFH) target service life. This is due to the poor crack-detectability of visual inspections combined with the fast crack growth observed at hot spots on flight-safety critical structure. The risk analysis demonstrates that improving the quality and frequency of inspections reduces the SFPOF to acceptable levels and achieves the target service life of the aircraft.