In a joint effort by the Federal Aviation Administration (FAA) and Delta Air Lines, the detailed inspection, destructive evaluation, and extended fatigue testing of a fuselage structure from a retired revenue-service passenger airplane was undertaken. Eleven large sections of fuselage representative of structure susceptible to widespread fatigue damage (WFD) were removed from a retired Boeing 727-232 airplane near its design service goal (DSG) of 60,000 flight cycles. This volume (volume 4 of a 5-volume report) documents the findings associated with the extended fatigue testing of two fuselage panels using the FAA Full-Scale Aircraft Structural Test Evaluation and Research facility. A simplified, once-per-flight, constant-amplitude load spectrum was used in the extended fatigue testing to simulate the airplane in-service loads, including the operational pressure and the vertical exceedances from a modified version of the transport wing structures spectrum. While testing, the lap joints of the panels were continuously assessed for damage development using high-magnification visual and nondestructive inspection methods. In the first panel tested, FT2, no cracks were detected in the panel skin test section after an additional 43,500 simulated flight cycles. The test was terminated due to extensive cracking in the load attachment points of the panel outside the test section. A posttest destructive evaluation found no nondetectable cracks. For the second test panel, FT1, an additional 120,000 flight cycles were applied with no crack indications in the test section, bringing the total life of the panel to three DSGs (180,000 flights). Artificial damage was then introduced into FT1 panel at select rivets in the critical (lower) rivet row, and the fatigue loads were increased. Visually detectable crack growth from the artificial notches was first seen after 133,000 cycles. The resulting lead crack grew along the lower rivet row, eventually forming an 11.8 long crack after 141,771 cycles, at which point the test was terminated. Results from this test will provide key data to support WFD assessments.
Destructive Evaluation and Extended Fatigue Testing of Retired Transport Aircraft. Volume 4: Extended Fatigue Testing
2007
306 pages
Report
No indication
English
Aircraft , Quality Control & Reliability , Joining , Nondestructive Testing , Transport aircraft , Fatigue tests(Mechanics) , Nondestructive testing , Crack propagation , Inspection , Joints , Rivets , Damage assessment , Panels , Aircraft components , Fuselages , Passenger aircraft , Test and evaluation , Lap joints
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