Continuing airworthiness concerns for aging jet transports has received much attention over the last 15 years.
Boeing and other TCH’s developed Supplemental structural inspection programs.
In the late1970’s and early 1980’s intended to address fatigue problems. And much focus was placed on fail safe structural designs.
The aloha incident became a milestone in respect of understanding the effects of widespread fatigue damage.
Whilst Boeing initiated aging ?eet surveys by engineering teams in the mid 1980’s, The Aloha explosive decompression incident became a milestone in respect of understanding the effects of widespread fatigue damage.
The primary method of driving Structural integrity relies on operator feed back together with Service Bulletin SB reviews and Mandatory Inspections (Sometimes AD driven sometimes Alert Service Bulletin Driven ASB).
Previously structural airworthiness integrity was wholly dependent on repetitive inspections. Aging airplane concerns prompted reassessment of the viability of repetitive inspections as a mechanism of protection.
The goal for the MRB structures working group is to preload integrity into the structure not rely on inspect, fix, report, followed by SB action and fleet campaigns.
Across the worlds fleets an accumulation of knowledge and experience has benefited current designs by an order of magnitude.
Corrosion Prevention and Control Programs (CPCP) were built into MSG3 programs. As we are aware If left unchecked corrosion has the potential to weaken structure which can lead to fatigue cracking, and a deterioration in Structural Integrity.
The individual characteristics of the CPCP programs vary between models and TCH but all follow the same basic principles to deliver an effective and managed approach to ensure all necessary areas are accessed inspected and treated in the approved manner .
To deliver EASA Continuing Airworthiness Related to Aircraft Structures in an effective way will require Procedures to ensure a full understanding by the mechanics of the purpose process and techniques to be used to ensure effective treatment is provided.
It is an unfortunate fact of life that Aircraft gather repairs with many of them being associated with ground damage. The Structure Repair Manual SRM is the first stop in assessing any newly found damage.
The SRM contains many standard type of repairs which may be performed, with larger repairs being managed by Part 21 approved organisations.
Whilst the primary need is for repairs to be compliant with the need for both static strength and fail safe attributes.
Increasingly when considering continuing airworthiness aspects, there is a need for ongoing inspection to ensure future detection of any deterioration. (is the existing MSG3 inspection process sufficient).
Repairs assessment thresholds are normally based on fatigue damage considerations and speci?ed for each aircraft model usually in ?ight cycles.
Typically varying between manufacturers, they are usually some based on 75% of design service objectives and range from 15,000 to 60,000 ?ight (depending on whether the operation is short haul or long haul).
The MSG3 analysis process includes assessments for environmental, accidental and fatigue damage as part of the Structures Working Group.
Damage detection is an critical element of maintaining damage tolerance assurance with training and knowledge being an essential element of the process how is your organization or maintainer managing the competencies of the inspection staff.
Sofema Aviation Services delivers regulatory training including Part M, Maintenance Program Management, Reliability and Production Planning.
Please see www.sassofia.com for details or email office@sassofia.com
