Two Questions: Who is responsible for airworthiness and where is it in the FARs?

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


Sub paragraph (c) says any aircraft with maintenance manual and a set of airworthiness limitations, those airworthiness limitations such as replacement times are mandatory unless superceded by alternative maintenance and inspections requirements on the operating specifications of Part 121 or 135 operator or an inspection program under section 91.409(e). This exception gives the air carriers some wiggle room to adjust the life limit items based on their data driven reliability programs.

Section 91.405 Maintenance required: Sub paragraph (a) says: Owner or operator shall have their aircraft inspected and have discrepancies repaired in accordance with Part 43. Again, there is an exception built into the rule for those inoperative items under sub paragraph (c) that allows those items to remain in an inoperative status and the aircraft can still be flown legally. A few decades ago when I could part my hair, this rule was more absolute. Back then; no aircraft could fly with inoperative equipment on board. This was changed about 10 years ago to grant some relief. I will talk more about it in sub paragraph (c).

Sub paragraph (b) states that the owner/operator shall ensure that maintenance personnel make appropriate entries and approve the work for return to service. This is a good example of parallel rule making. As a mechanic, Part 43, sections 43.9 and 43.11 require you to make maintenance entries. So in an effort to make sure these records are made, the drafters of this Subpart made the owner/operator responsible for checking the mechanic so that he made the entries in the logbook that he is required to make by another rule. Trusting souls weren?t they.

Sub paragraph (c) states the owner/operator shall have any inoperative instrument or item of equipment permitted to be inoperative by section 91.213(d)(2) to be repaired, replaced, removed, or inspected at the next required inspection. Section 91.213 inoperative instruments and equipment allows aircraft without a minimum equipment list to fly with inoperative instruments or equipment on board only if they are not part of the required VFR-day type certificated instruments/equipment, or required by any other rule.

For example, a rotating beacon on a PA 28-140 no longer rotates. That inoperative beacon can remain on the aircraft for years because a rotating beacon is not required for day VFR operation. However, please remember that this is not a one-time inspection. At each required inspection you must inspect the beacon and check that it is in compliance with Section 91.213. Then you must sign off that Section 91.213 inspection in the logbook for as long as that inoperative beacon is on the aircraft. For additional information on Section 91.213 is found in AC 91.67.

Paragraph (d) says the owner or operator must ensure that a placard be installed for all inoperative equipment as required by section 43.11. All this means that in our previous example the rotating beacon on/off switch must be placarded ?INOP?. In some cases the beacon?s circuit breaker is collared. All these precautions notify the pilot that the aircraft is not legal for night VFR flights.

Section 91.407. Operation after maintenance, preventive maintenance, rebuilding or alteration. Sub paragraph (a)(1) of this rule requires the owner/operator to have an approval for return to service statement in the logbook prior to flight. Sub paragraphs (a)(2) require a maintenance entry in accordance with Part 43.9 and 43.11. So far sub paragraphs (1) and (2) are just a rehash of the requirements under sections 91.403 and 91.405. It?s sort of like being trapped in a regulatory cul-de-sac.

Sub paragraph (b) is important. This paragraph requires an aircraft to undergo a test flight if it has been maintained, rebuilt, or altered in a manner that might appreciably change its flight characteristics or substantially affect its operation. The test flight has to be performed by an appropriately rated pilot with at least a private pilot certificate. After the flight, the pilot must record the flight in the logbook and state that the aircraft is operational and safe to fly.

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