METHOD AND APPARATUS FOR MONITORING AIRCRAFT FUSELAGE DETERIORATION

In a pressurized aircraft, the net air leakage occurring while the aircraft is pressurized at altitude, i.e., the difference between the mass flow rate of all air supplied to the pressurized compartments of the aircraft and the mass flow rate of all air intentionally discharged to the external ambient, is calculated by a system employing air mass flow gauges in the air supply and discharge ducts. Increases in the rate of leakage over time furnish an indication of deterioration of the aircraft structure such as that caused by fatigue and stress corrosion of the external skin.