Definition:
Airworthiness Directives (ADs) are legally enforceable regulations issued by the authority to correct an unsafe condition in a product. product may be an aircraft, engine, propeller, system, units or appliance.
When Authority issue Airworthiness Directives?
ADs usually result from safety issue reported by operators or from the results of aircraft incident/ accident investigations. They are issued either by the national civil aviation authority of the country of aircraft manufacture or of aircraft registration. When ADs are issued by the country of registration they are almost always coordinated with the civil aviation authority of the country of manufacture to ensure that conflicting ADs are not issued.
Who can issue Airworthiness Directives?
Airworthiness Directive AD issued either by:
- the national civil aviation authority of the country of aircraft manufacture, for example EASA (Airbus) and FAA (Boeing).
- Local civil aviation authority of the state of registration.
When ADs are issued by the country of registration they are almost always coordinate with the civil aviation authority of the country of manufacture to ensure that no conflict.
What are the AD types?
The AD types and roles differ from authority to other but here we will take a look on the most popular in commercial and non-commercial aviation field EASA and FAA
EASA classification:
1- Mandatory Continuing Airworthiness Information MCAI
All mandatory Airworthiness Directives containing emergency airworthiness directives and proposed airworthiness directives.
2- Sensitive Security Airworthiness Directive (SSAD)
An SSAD is an AD issued or adopted by EASA that mandates certain corrective actions, the content of which includes security sensitive information.
An SSAD record is uploaded in the EASA Safety Publications publishing tool, but only after the end of the SSAD compliance time and without attachments;
3- Alternative Methods of Compliance to Airworthiness Directives (AMOC to ADs)
An Alternative Method of Compliance (AMOC) is an EASA approved deviation to an AD. It is a different way, other than the one specified in an AD, to address an unsafe condition on products, parts and appliances. An AMOC must provide an acceptable level of safety, equivalent to the level of safety intended for compliance with the original AD.
4- Non-EU Member State Airworthiness Directives
For products, parts and appliances, for which the Agency only exercises the design responsibilities of the State of Registry, its policy is to endorse automatically the airworthiness directives issued by the State of Design, except if it itself issues a different airworthiness directive or a decision to not adopt the airworthiness directive (Executive Director Decision .
5- Proposed Airworthiness Directive PAD
In this consultation period of Proposed Airworthiness Directives (PAD), EASA allows users to submit their comments via Safety tool
6- Emergency Airworthiness Directive EAD
In this type of airworthiness directives often all affected product grounded until corrective action taken to the emergency unsafe condition.
FAA classification:
1- Notice of Proposed Rulemaking (NPRM), followed by a Final Rule
After discover condition affect safety or result of accident /incident investigation, the proposed solution is published as an NPRM Notice of Proposed Rulemaking, which solicits public comment on the proposed action
2- Final Rule; Request for Comments
After the comment period closes, the final rule is prepared, considering all substantive comments received, with the rule perhaps being changed as warranted by the comments the preamble to the final rule AD will provide response to the substantive comments or state there were no comments received.
3- Emergency ADs
In certain cases, the critical nature of an unsafe condition may warrant the immediate adoption of a rule without prior notice and solicitation of comments. This is an exception to the standard process.
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