Pressurisation Cycle Fatigue
Definition
Fatigue damage driven by the repeated inflation and deflation of the aircraft fuselage as it climbs to altitude and descends. Each flight is approximately one cycle; modern narrow-body jets are certified for tens of thousands of cycles.
- Driver
- Repeated cabin inflation and deflation
- Cycle unit
- Approximately one cycle per flight
- Certification
- Tens of thousands of cycles for narrow-body jets
- Affected structure
- Aircraft fuselage
Common questions
Why is pressurisation cycle fatigue distinct from flight-hour based fatigue?+
Cycle fatigue accumulates each time the fuselage is stressed by a pressurisation and depressurisation event regardless of flight duration, so a fleet of short-hop aircraft can accumulate fatigue cycles faster relative to flight hours than long-haul aircraft, which is why cycle count is tracked separately from total flight hours.
How does pressurisation cycle fatigue investigation differ after a fuselage failure?+
Investigators examine the fracture surface for fatigue striations and count them where possible to estimate the number of cycles the crack propagated through, cross-referencing that count against the aircraft's maintenance and cycle history to assess whether inspection intervals or repair history contributed to the failure.
Related terms
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- NTSB / AAIB
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- On-Condition Maintenance
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