If you ask a general aviation mechanic this question: ?Who is primarily responsible for the airworthiness of the aircraft?? Young or old, he will answer immediately and without batting an eye: ?Owner or operator!? And he would be right.
Then I set them up for the next question. ?Where does it say in the FARs that owners and operators are primarily responsible for the airworthiness of the aircraft?? Few mechanics can answer that question correctly.
The correct answer to the question, I say in my best bureaucratic voice, is found in Part 91, Subpart E, Maintenance, preventive maintenance and alterations, section 91. 403 (a) General. Then I go on to tell them that Part 91 Subpart E has 12 individual rules or sections that pertain to maintenance and then I start on a three-hour, mind-numbing lecture that covers all of Subpart E of Part 91.
This article will cover only the first four rules of the subpart. It is my hope that I might provide an insight or two into this subpart and perhaps even encourage one or two of you to take on the task of actually reading the rest of the rules in Subpart E.
Before we get into it, there are two concepts I need you to understand. First, Part 91 is talking only to the owner/operator responsibilities for performing maintenance, not mechanics. So why involve mechanics? Because more often than not, a mechanic, acting as the owner?s agent will be doing the scheduling, inspections, and record keeping required by this subpart. So, in order to keep the owner out of trouble, mechanics need to know these rules.
Second item. Part 91 is an ?operating? based rule, unlike Part 43, which is a ?performance based rule.? This operating and performance concept is the major difference between the two rules. Allow me to take a shot at explaining this. If you performed an unairworthy repair on an aircraft and signed it off as required by Part 43 section 43.9 and the aircraft never flew, a FAA inspector can write a violation against you for the bad repair. To get a violation written against an owner/operator for not complying with a Part 91 Sub-Part E rule, the aircraft had to be operated for the violation to happen. For example if the annual is pass due by five years and the aircraft never is operated, then no violation has occurred under this Subpart.
With that said, let us press on.
Section 91. 401 Applicability. In this su bpart sub paragraph (a) prescribes the rules governing the maintenance, preventive maintenance, and alterations of U.S registered aircraft operating in or outside the United States. Note again the use of the word ?operating,? as in ?world wide.? The rest of this section?s sub paragraphs (b) and (c) grants relief to Part 121, 125, 129 and 135 operators from certain sections of the Subpart because of the different maintenance program, those operators are required to be under.
Section 91. 403 General. Sub paragraph (a) very clearly states that the owner or operator is primarily responsible for maintaining the aircraft in an airworthy condition of the aircraft including compliance with Part 39, Airworthiness Directives, of this chapter. While the owner or operator is primarily responsible by this rule it does not relieve the pilot from the responsibility of determining the airworthiness of the aircraft prior to and during a flight (Ref: Section 91.7) or a mechanic from performing airworthy repairs (Ref: Section 43.13).
Sub paragraph (b) starts with: No person may perform maintenance, preventive maintenance or alterations on an aircraft other than as prescribed in this subpart and other applicable regulations including Part 43 of this chapter. This is a clarifying statement that says all applicable rules apply and reinforces paragraph (a). Government lawyers do this all the time to prevent confusion and possible conflict between different Parts or sections. They are not always successful.