Undocumented parts

May 1, 1998

Undocumented Parts

By Brian Whitehead

May-June 1998

Brian Whitehead is chief of policy development for the Aircraft Maintenance & Manufacturing branch in Ottawa, Canada.

Undocumented parts have been in the news quite a bit lately, and several aviation authorities have launched initiatives to address this topic. One of those initiatives passed a major milestone in April, when a package of regulatory changes received the approval of the Canadian Aviation Regulation Advisory Committee (CARAC). The proposed changes, which were developed by a Transport Canada/Industry working group, will now be submitted for formal public consultation through the Canada Gazette process before publication in the Canadian Aviation Regulations (CARs). Once formally approved, they will provide for a recognized means of evaluating undocumented parts, to determine whether they can be recertified and re-introduced into the aviation system.

The changes involve several sections of the regulations, primarily CAR 571.07, Installation of New Parts; CAR 571.08, Installation of Used Parts; CAR 571.09, Installation of Life Limited Parts; CAR 571.10, Maintenance Release; CAR 571.13, Installation of Parts (General); CAR 573.02, Approved Maintenance Organization (AMO) Certificates; and CAR 573.05, Qualifications for Signing a Maintenance Release. Additionally, the proposals call for a new 571 Appendix H, to address the procedures for the control of undocumented parts. The procedures will include a flow chart and decision tree for the processing of undocumented parts as well as guidance regarding the examination and testing of such parts with a view to recertifying them as legitimate aeronautical products. The aim of the evaluation is to establish if the parts conform to the applicable type design and are in a condition for safe operation.

Certain kinds of parts will not be eligible for evaluation under this process. These include life-limited parts and any parts that are required by the applicable instructions for continued airworthiness to be rejected following an unusual occurrence, such as overspeed or overtemp. The principle applied here is, in the absence of firm evidence, to always assume the worst case. For example, if the origin of a set of turbine blades is not known, then it must be assumed that the blades could have been installed in an engine that has been subject to excessive temperature. If no valid test exists to refute this assumption, the blades must be rejected. Also excluded will be parts that are approved for installation in multiple applications, where one or more of those applications are subject to life limits or rejection after certain occurrences. For example, if a part is subject to a life limit in one application, but not in another, it must be assumed that the part has been subject to the life-limited conditions, which would require it be rejected if the actual history of the part is not known.

The privilege of performing evaluations of undocumented parts will be restricted to AMOs who have been specifically authorized to perform this function. A new AMO rating will be created to indicate those AMOs who are so qualified. The rating will be limited to specific kinds of aeronautical parts, for which the AMO has demonstrated effective evaluation procedures. The parts must be of a kind that fall within the AMOs existing maintenance privileges. The AMO will be required to document the standards and procedures applied under these new provisions and obtain Transport Canada approval for the specific procedures used.

Strict controls will also apply to the persons who are authorized to issue the certification following evaluation of the parts. The proposals call for these individuals to have at least five years experience as an approved signatory with Aircraft Certifying Authority (ACA) on the type of aircraft involved, or Shop Certifying Authority (SCA) on the kinds of parts involved. The individual must successfully complete a course of training on the evaluation procedures to be used.

Guidance will also be provided on the disposal of life-limited parts that have completed their allowable time in service, or for which the time in service is unknown. The new rules will emphasize the necessity of properly identifying parts, and segregating airworthy parts from unairworthy parts and from parts of unknown origin. The proposed changes recognize that, in parts that are not subject to the stringent controls on life limits, it may not always be possible to trace the part's history all the way back to its point of origin. In such cases, traceability back to the last documented time of installation on an airworthy aeronautical product will be acceptable.

Finally, the new requirements provide additional guidance on generic parts in common use, including definitions of "standard" and "commercial" parts and additional guidance regarding parts that were originally designed for nonaeronautical use, that have since been approved for installation on aircraft. Examples of the latter include some automotive parts that have been incorporated into the design of certain small aircraft.

Taken together, the changes provide a means for acceptance of genuine aeronautical products that for one reason or another may have become separated from their proof of origin, while ensuring that our primary concern of safety is not compromised. These proposals are a first step toward solving a widespread problem. Transport Canada will continue to work with other authorities with the aim of achieving a harmonized global solution to the undocumented parts issue.