A primary safety function of the FAA is to require correction of unsafe conditions found in an aircraft, aircraft engine, propeller, or appliance hen such conditions exist or are likely to exist or develop in other products of the same design. The unsafe conditions can exist because of a design defect, maintenance, or other causes. FAR Part 39, Airworthiness Directives, (AD) defines the authority and responsibility of the Administrator for requiring the necessary corrective action. AD's are used to notify aircraft owners and other interested persons of unsafe conditions and to specify the condition under which the product may continue to be operated.
AD's may be divided into two categories:
1. Those of an emergency nature requiring immediate compliance prior to further flight, and
2. Those of a less urgent nature requiring compliance within a relatively longer period of time.
AD's are FAR's and all be complied with, unless specific exemption is granted. It is the aircraft owner's or operations responsibility to ensure compliance with all pertinent AD's. This includes those AD's that require recurrent or continuing action. For example, an AD may require a repetitive inspection each 50 hours of operation, meaning the particular inspection shall be accomplished and recorded every 50 hours of time in service. Owner/operators are reminded there is no pr vision to overfly the maximum hour requirement of an AD unless it is specifically written into e AD. To help you determine if an AD applies to an amateur-built aircraft, contact your local DO.
FAR Section 91.417 requires a record to be maintained that shows the current status of applicable AD's, including the method of compliance, the AD number and revision date, if recurring, the time and date when due again, the signature, kind of certificate, and number of the repair station or mechanic who performed the work. For ready reference, many aircraft owners have a chronological listing of the pertinent AD's in back of their aircraft and engine records.
The Summary of Airworthiness Directives contains all valid AD's previously published. The current AD's are published in a biweekly supplement. The AD's are divided into two books: Book One is the Rotorcraft and Small Aircraft under 12,500 pounds maximum certificated takeoff weight; and Book Two is the Large Aircraft over 12,500 pounds. These books and the biweekly supplement are available for purchase in paper copy, microfiche, or electronic format.
Advisory Circular 39-7, Airworthiness Directives, provides additional guidance and information for complying with and recording AD's.
To order AD's from the FAA, contact Manufacturing Standards Section, AFS-613 in Oklahoma City, OK, telephone (405) 954-4103, or fax (405) 954-4104. (FAR Part 39)
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