To manage Airworthiness Standards Airbus Industry has developed a six part Airworthiness Section to support the Maintenance Planning Document (MPD). Airworthiness standards are not only set for the design of the aircraft but also for operation and maintenance while in service. The Maintenance Program is typically under continuous development and must demonstrate compliance with the Regulatory Framework, requirements include satisfying. Certification Specification (CS) and Federal Aviation Requirement (FAR).
CS/FAR 25.1529 Instructions for continued airworthiness requiring that “Instructions for Continued Airworthiness in accordance with Appendix H must be prepared.” Also of major importance to the airline is the economic success of the operation, the process which is used to develop the MPD (Maintenance Steering Group 3 (MSG3) actually considers economic benefits during the development of the maintenance process.
Airline operation require comprehensive maintenance instructions to keep level of safety, reliability and availability at minimum cost. Scheduled Maintenance Requirements driven by the MPD identify a group of scheduled maintenance tasks to be accomplished at specified intervals. The objective of these tasks is to either prevent deterioration of the inherent safety and reliability levels of the aircraft. Or to provide a specific economic benefit.
The Different Parts of the Airbus ALS
Driven by Structural Considerations we have two Airworthiness Limitation Sections – During the design phase we must be able to show structural compliance with CS /FAR 25-571 perform Fatigue analysis and develop both Safe Life and Fail Safe considerations
Note
Fail safe is a design philosophy where all critical components (wing spars, main structural members) can fail and the load would be transferred to another structure safely, if with reduced margins. Also called “redundant” design.
Safe life is applied to limit the maximum service life of a component, by testing and/or calculations using the known properties of the component’s materials.
Safe Life – Safe Life Airworthiness Limitation Items ALS Part 1.
Fail Safe – Damage Tolerance Analysis – leading to Damage Tolerant Airworthiness Limitation Items ALI ALS Part 2.
Driven by Systems Considerations we also have 2 Airworthiness Limitation Sections – Commercial Aircraft Systems must show compliance with CS / FAR 25-1309
We have two elements to consider and the difference is driven by the Design Service Goal (DSG):
1) System Safety Assessment (SSA) pre Design Service Goal (DSG) + Maintenance Steering Group 3 Analysis provides for Certification Maintenance Requirements (CMR) ALS Part 3
2) And System Safety Assessment (SSA) post Design Service Goal (DSG) + Maintenance Steering Group 3 Analysis + System Life Limits provides for Aging System Maintenance ASM ALS Part 4
In respect of the Fuel system we have to show compliance to Fuel to show compliance with CS /FAR 25-981
Fuel Tank /System Analysis leading to Fuel Airworthiness Limitations ALS Part 5
ALS Part 6 is a recent addition and concerns Aircraft Information System Security (AISS)
The following list provides an example of AISS safety issues:
– Safe and reliable aircraft (airframe systems)
– Safe and reliable navigation – Takeoff, landing, in-route (airway) navigation
– Collision avoidance, Position-Location
– Safe and secure cockpit and cabin
– Secure and reliable aircraft communications
– Air-to-ground 2-way communications, Air-to- Air 2-way communications
– Air Traffic Control radar transponder
– Cockpit Voice Recorder
– Flight Data Recorder
Tags:
Airworthiness Limitations, AISS, ALS, Maintenance Planning Document, Maintenance Steering Group 3, MPD, MSG3
