Aircraft Systems

Aircraft Routine/Required Inspections

For the purpose of determining their overall condition, 14 CFR provides for the inspection of all civil aircraft at specific intervals, depending generally upon the type of operations that they are engaged in. The pilot in command (PIC) of a civil aircraft is responsible for determining whether that aircraft is in a condition for safe flight. Therefore, the aircraft must be inspected before each flight. More detailed inspections must be conducted by aviation maintenance technicians (AMTs at least once each 12 calendar months, while inspection is required for others after each 100 hours of flight. In other instances, an aircraft may be inspected in accordance with a system set up to provide for total inspection of the aircraft over a calendar or flight time period. These include phase-type inspections.

To determine the specific inspection requirements and rules for the performance of inspections, refer to the CFR that prescribes the requirements for the inspection and maintenance of aircraft in various types of operations.

Preflight/Postflight Inspections

Pilots are required to follow a checklist contained within the Pilot’s Operating Handbook (POH) when operating aircraft. The first section of the checklist is entitled “Preflight Inspection.” The preflight inspection checklist includes a “walk-around” section listing items that the pilot is to visually check for general condition as he or she walks around the airplane. Also, the pilot must ensure that fuel, oil, and other items required for flight are at the proper levels and not contaminated. Additionally, it is the pilot’s responsibility to review the aircraft maintenance records, and other required paperwork to verify that the aircraft is indeed airworthy. After each flight, it is recommended that the pilot or mechanic conduct a postflight inspection to detect any problems that might require repair or servicing before the next flight.

Annual/100-Hour Inspections

The basic requirements for annual and 100-hour inspections are discussed in 14 CFR part 91. With some exceptions, all aircraft must have a complete inspection annually. Aircraft that are used for commercial purposes (carrying any person, other than a crewmember, for hire or flight instruction for hire) and are likely to be used more frequently than noncommercial aircraft must have this complete inspection every 100 hours. The scope and detail of items to be included in annual and 100-hour inspections is included as Appendix D to part 43. [Figure 1]

Aircraft Routine/Required Inspections
Figure 1. Title 14 CFR Appendix D to Part 43—Scope and detail of items (as applicable to the particular aircraft) to be included in annual and 100-hour inspections

A properly written checklist, such as the one shown in this site, includes all the items of Appendix D. Although the scope and detail of annual and 100-hour inspections are identical, there are two significant differences. One difference involves persons authorized to conduct them. A certified airframe and powerplant (A&P) maintenance technician can conduct a 100-hour inspection, whereas an annual inspection must be conducted by a certified A&P maintenance technician with inspection authorization (IA). The other difference involves authorized overflight of the maximum 100 hours before inspection. An aircraft may be flown up to 10 hours beyond the 100-hour limit if necessary to fly to a destination where the inspection is to be conducted.

Progressive Inspections

Because the scope and detail of an annual inspection is very extensive and could keep an aircraft out of service for a considerable length of time, alternative inspection programs designed to minimize down time may be utilized. A progressive inspection program allows an aircraft to be inspected progressively. The scope and detail of an annual inspection is essentially divided into segments or phases (typically four to six). Completion of all the phases completes a cycle that satisfies the requirements of an annual inspection. The advantage of such a program is that any required segment may be completed overnight and thus enable the aircraft to fly daily without missing any revenue earning potential. Progressive inspection programs include routine items, such as engine oil changes, and detailed items, such as flight control cable inspection. Routine items are accomplished each time the aircraft comes in for a phase inspection, and detailed items focus on detailed inspection of specific areas. Detailed inspections are typically done once each cycle. A cycle must be completed within 12 months. If all required phases are not completed within 12 months, the remaining phase inspections must be conducted before the end of the 12th month from when the first phase was completed.

Each registered owner or operator of an aircraft desiring to use a progressive inspection program must submit a written request to the FAA Flight Standards District Office (FSDO) having jurisdiction over the area that the applicant is located. Section 91.409(d) of 14 CFR part 91 establishes procedures to be followed for progressive inspections. [Figure 2]

Aircraft Routine/Required Inspections
Figure 2. Title 14 CFR Section 91.409(d), Progressive Inspection

Continuous Inspections

Continuous inspection programs are similar to progressive inspection programs, except that they apply to large or turbine-powered aircraft and are therefore more complicated. Like progressive inspection programs, they require approval by the FAA Administrator. The approval may be sought based upon the type of operation and the CFR parts that the aircraft is operated under. The maintenance program for commercially operated aircraft must be detailed in the approved operations specifications (OpSpecs) of the commercial certificate holder.

Airlines utilize a continuous maintenance program that includes both routine and detailed inspections. However, the detailed inspections may include different levels of detail. Often referred to as “checks,” the A-checks, B-checks, C-checks, and D-checks involve increasing levels of detail. A-checks are the least comprehensive and occur frequently. D-checks, on the other hand, are extremely comprehensive, involving major disassembly, removal, overhaul, and inspection of systems and components. They might occur only three to six times during the service life of an aircraft.

Altimeter and Transponder Inspections

Aircraft that are operated in controlled airspace under instrument flight rules (IFR) must have each altimeter and static system tested in accordance with procedures described in 14 CFR part 43, Appendix E, within the preceding 24 calendar months. Aircraft having an air traffic control (ATC) transponder must also have each transponder checked within the preceding 24 months. All these checks must be conducted by appropriately certified individuals.

Aircraft Special Inspections
Nondestructive Inspection/Testing (Part 1)
Nondestructive Inspection/Testing (Part 2)
Inspection of Aircraft Bonded Structures (Part 1)