Jetrader - March/April 2011 - 21

Breaking Up is Hard(er) to Do
By Don Mitchell Miami’s “Corrosion Corner” is getting busier. In January, the Federal Aviation Administration’s (FAA) new rules addressing widespread fatigue damage (WFD) in aging aircraft became effective. Drafted as amendments to Parts 25, 26, 121 and 129 of the U.S. Federal Aviation Regulations (FARs), the FAA has effectively set “soft” life limits for aircraft. While these regulations only affect U.S.registered aircraft, it is expected that EASA and other regulators will follow suit. The issue of WFD gained widespread attention in April 1988 when the upper fuselage of an Aloha Airlines 737 separated in flight. While not caused exclusively by fatigue, the era of increased scrutiny of the maintenance of aging aircraft formally began. In fact, the FAA began efforts in the 1970s to address fatigue damage in aircraft when it transitioned from a “fail safe” to “damage tolerance” approach, according to Ray Valeika, former airline executive and most recently the former Senior Vice President of Technical Operations at Delta Air Lines. According to Valeika, the “fail safe” approach sought to prevent any fatigue damage to aircraft structures. As a result, Valeika said, inspections were time-consuming and aircraft were over-engineered to provide a cushion of protection. The “damage tolerance” approach, Valeika explained, presumes that some fatigue damage will exist, but aims to manage it through targeted inspections based on engineering analysis to detect and repair it before a structural failure occurs. Design service goals were expectancies that could be exceeded with a “detect and repair” aging aircraft inspection program. Under “damage tolerance,” the concern is not fatigue cracking itself. Small fatigue cracks occur over the course of an aircraft’s life. However, unless discovered during inspection, small cracks in close proximity can rapidly and unexpectedly join to make large cracks. Engineered tear stoppers were the last defense against a catastrophic failure if cracks remained undetected. More recently and following a number of news-making in-flight decompressions, the FAA concluded that aircraft inspections that sometimes uncovered fatigue cracks by happenstance and the patchwork of Airworthiness Directives (ADs) that addressed them didn’t go far enough. “More cracks resulted in more ADs, which then became a very complicated way to manage aircraft structure,” Valeika said. “This new rule is a way to amalgamate how you handle this issue.” The “damage tolerance” approach is not dead; it is now just part of a broader approach to WFD. The new rules apply to turbine-powered aircraft certificated after 1 January 1958, which have a maximum takeoff gross weight greater than 75,000 pounds and which are operated under FAR Parts 121 or 129. Boeing 707s and Caravelles, among Jetrader 21

The FAA requires design approval holders to demonstrate that their aircraft will not suffer from WFD during their design service lives.



Jetrader - March/April 2011

Table of Contents for the Digital Edition of Jetrader - March/April 2011

Jetrader - March/April 2011
A Message from the President
Table of Contents
Calendar/News
Q&A: David Neeleman
Aircraft Financing 2011: Expanding Liquidity Meets More Deliveries
Mind the Generation Gap
Breaking Up is Hard(er) to Do
State of the Regions: North America
‘You’re Late on the Payments!’
Relationships Versus Brand Marketing in Aviation
Aircraft Appraisals
Aviation History
Advertiser.com/ Advertiser Index
Jetrader - March/April 2011 - Jetrader - March/April 2011
Jetrader - March/April 2011 - Cover2
Jetrader - March/April 2011 - A Message from the President
Jetrader - March/April 2011 - 4
Jetrader - March/April 2011 - Table of Contents
Jetrader - March/April 2011 - 6
Jetrader - March/April 2011 - Calendar/News
Jetrader - March/April 2011 - Q&A: David Neeleman
Jetrader - March/April 2011 - 9
Jetrader - March/April 2011 - 10
Jetrader - March/April 2011 - 11
Jetrader - March/April 2011 - Aircraft Financing 2011: Expanding Liquidity Meets More Deliveries
Jetrader - March/April 2011 - 13
Jetrader - March/April 2011 - 14
Jetrader - March/April 2011 - 15
Jetrader - March/April 2011 - 16
Jetrader - March/April 2011 - Mind the Generation Gap
Jetrader - March/April 2011 - 18
Jetrader - March/April 2011 - 19
Jetrader - March/April 2011 - 20
Jetrader - March/April 2011 - Breaking Up is Hard(er) to Do
Jetrader - March/April 2011 - 22
Jetrader - March/April 2011 - 23
Jetrader - March/April 2011 - State of the Regions: North America
Jetrader - March/April 2011 - 25
Jetrader - March/April 2011 - 26
Jetrader - March/April 2011 - 27
Jetrader - March/April 2011 - 28
Jetrader - March/April 2011 - ‘You’re Late on the Payments!’
Jetrader - March/April 2011 - 30
Jetrader - March/April 2011 - 31
Jetrader - March/April 2011 - Relationships Versus Brand Marketing in Aviation
Jetrader - March/April 2011 - 33
Jetrader - March/April 2011 - 34
Jetrader - March/April 2011 - Aircraft Appraisals
Jetrader - March/April 2011 - 36
Jetrader - March/April 2011 - 37
Jetrader - March/April 2011 - 38
Jetrader - March/April 2011 - 39
Jetrader - March/April 2011 - 40
Jetrader - March/April 2011 - Aviation History
Jetrader - March/April 2011 - 42
Jetrader - March/April 2011 - 43
Jetrader - March/April 2011 - 44
Jetrader - March/April 2011 - Advertiser.com/ Advertiser Index
Jetrader - March/April 2011 - 46
Jetrader - March/April 2011 - Cover3
Jetrader - March/April 2011 - Cover4
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