Briefing: amended Civil Aviation Order 100.5
The amendment to Civil Aviation Order 100.5 and the cancellation of AD/INST/8, INST/9 and RAD/43 was published for comment in September 2011, with the comment period closing in November 2011.
The intent was to ensure the maintenance of altimeters, air speed indicators, pitot-static systems, and fuel gauges was done to a single standard for VFR and IFR aircraft when they both operate in the same airspace. Aircraft that have existing systems of maintenance, or maintenance schedules that incorporate the standards detailed in Appendix 1 of the Order, are exempt from compliance.
For aircraft that have been maintained in accordance with the cancelled ADs and are affected by the transitional arrangements, the operators may request an extension to the transitional time limits to align with the planned retest.
To clarify terminology CAO 100.5 has introduced the term "Certification Maintenance" (CMRs) and Airworthiness Limitations (AWL). CMRs arise from the aircraft type certification process. FAR 25.1309, for example, requires a System Safety Assessment (SSA) to ensure that failures are categorized on their consequential severity and within defined bounds of probability. A CMR is a required periodic task, established during the design certification of the aircraft as an operating limitation of the type certificate. CMRs usually result from a formal, numerical analysis conducted to show compliance with catastrophic and hazardous failure conditions. A CMR is intended to detect safety significant latent failures that would, in combination with one or more other specific failures or events, result in hazardous or catastrophic failure condition.
AWLs are structural items that the certification process has defined as critical from a fatigue point of view during the damage tolerance assessment. The inspection frequency of such items is mandatory. Many older aircraft include AWLs in the same chapter of the maintenance manual where they included recommended overhaul period.
A more comprehensive description of these issues has been published in AWB 00-022 Issue 1 - Certification Maintenance Requirement and Airworthiness Limitations Terminology Explained .
This amendment to CAO 100.5 does not affect the application of existing Airworthiness Directives such as AD/ENG/4, AD/PROP/1 etc.
View a copy of the complete CAO 100.5