Instructions for Continued Airworthiness
By Brian Whitehead
Things used to be so straightforward. We had the manufacturer’s maintenance manual, and that was that. Now we have the "Type Certificate Holder’s Instructions for Continued Airworthiness (ICA)." Sometimes, we even see "Instructions for Continued Airworthiness or Manufacturer’s Maintenance Manual." Other than a bureaucratic tendency to never be satisfied with one word where half a dozen will do, what’s the difference?
In practice, not a lot. Obviously, the traditional maintenance manual contained instructions for continued airworthiness. Yet, a couple of points are worth noting. First, despite some regulatory references to the contrary, which will be amended in due course, ICAs are the responsibility of the type certificate holder, not the manufacturer. At one time, the two terms were synonymous, but that is no longer the case. That brings us to the second point — the new terminology coincided with the inclusion of ICA as a condition for type certification. In the case of transport category aeroplanes, STD 525.1529 requires the applicant to "—prepare Instructions for Continued Airworthiness in accordance with Appendix H to this chapter that are acceptable to the Minister." Similar provisions apply to other categories, and to modifications approved by Supplemental Type Certificate (STC).
Some "acceptable" confusion
That word "acceptable" has confused some people, leading them to ask whether ICAs are approved or not. The fact is, it really doesn’t matter. Actually, about the only maintenance recommendations that do need approval are those that result in a major change to the product. That’s why Structural Repair Manuals (SRMs) are sometimes approved, because the repairs described may cause the product to deviate from its original approved design. Even those approvals may not really be necessary under the Canadian domestic system, because the CARs recognize the concept of "specified data," i.e., data from sources the Minister has specified as not requiring approval. The SRM is one such source. However, since other authorities may not have similar provisions, SRMs might be approved for use in those foreign jurisdictions.
So, what does "acceptable" mean? Well, in this context, it’s merely the standard to be met. Unlike the design standards for structures and systems, which often involve quantitative criteria, this standard is qualitative. Instead of specifying a rigid format, style, and content; it simply states that ICAs have to be acceptable to the Minister. To avoid this standard being too subjective, the applicable appendices provide information on the main features to be included.
The appendices require ICAs to be in the form of a manual or manuals, leading to the question of whether or not service bulletins are included. In practice, that depends on the circumstances. Applicants for a type certificate have to submit a program to show how changes to the ICAs will be distributed, and the service bulletin system is often part of that program. For some small, basic aircraft, it may well constitute the entire program. Therefore, in the absence of a specific statement to the contrary, service bulletins and equivalent publications should be regarded as part of the ICA. A degree of judgment is required here, because some manufacturers, as a service to their customers, publish newsletters or other semi-official advisory publications that are not intended to be formal recommendations. Usually, such publications contain a disclaimer to that effect.
FAA, EASA and TCCA are developing a regulatory impact assessment to define areas of common interest. This project is expected to last through 2012.
Implications for continued airworthiness and corrosion control
When you speak about aircraft maintenance, confusion is best left to the experts when tackling acceptable and approved.