It has been proven that regularly scheduled inspections and preventive maintenance assure airworthiness. Operating failures and malfunctions of equipment are appreciably reduced if excessive wear or minor defects are detected and corrected early. The importance of inspections and the proper use of records concerning these inspections cannot be overemphasized.
Airframe and engine inspections may range from preflight inspections to detailed inspections. The time intervals for the inspection periods vary with the models of aircraft involved and the types of operations being conducted. The airframe and engine manufacturer’s instructions should be consulted when establishing inspection intervals.
Aircraft may be inspected using a flight hours inspection system, a calendar inspection system, or a combination of both. Under the calendar inspection system, the appropriate inspection is performed on the expiration of a specified number of calendar weeks. The calendar inspection system is an efficient system from a maintenance management standpoint. Scheduled replacement of components with stated hourly operating limitations is normally accomplished during the calendar inspection falling nearest the hourly limitation. In some instances, a flight hour limitation is established to limit the number of hours that may be flown during the calendar interval.
Aircraft operating under the flight hour system are inspected when a specified number of flight hours are accumulated. Components with stated hourly operating limitations are normally replaced during the inspection that falls nearest the hourly limitation.
Before starting an inspection, be certain all plates, access doors, fairings, and cowling have been opened or removed and the structure cleaned. When opening inspection plates and cowling, and before cleaning the area, take note of any oil or other evidence of fluid leakage.
In order to conduct a thorough inspection, a great deal of paperwork and/or reference information must be accessed and studied before proceeding to the aircraft to conduct the inspection. The aircraft logbooks must be reviewed to provide background information and a maintenance history of the particular aircraft. The appropriate checklist or checklists must be utilized to ensure that no items are forgotten or overlooked during the inspection. Also, many additional publications must be available, either in hard copy or in electronic format, to assist in the inspections. These additional publications may include information provided by the aircraft and engine manufacturers, appliance manufacturers, parts vendors, and the Federal Aviation Administration (FAA).
“Aircraft logs,” as used in this handbook, is an inclusive term that applies to the aircraft logbook and all supplemental records concerned with the aircraft. They may come in a variety of formats. For a small aircraft, the log may indeed be a small 5″ × 8″ logbook. For larger aircraft, the logbooks are often larger and in the form of a three-ring binder. Aircraft that have been in service for a long time are likely to have several logbooks.
The aircraft logbook is the record where all data concerning the aircraft is recorded. Information gathered in this log is used to determine the aircraft condition, date of inspections, time on airframe, engines, and propellers. It reflects a history of all significant events occurring to the aircraft, its components, and accessories. Additionally, it provides a place for indicating compliance with FAA airworthiness directives (ADs) or manufacturers’ service bulletins (SB). The more comprehensive the logbook, the easier it is to understand the aircraft’s maintenance history.
When the inspections are completed, appropriate entries must be made in the aircraft logbook certifying that the aircraft is in an airworthy condition and may be returned to service. When making logbook entries, exercise special care to ensure that the entry can be clearly understood by anyone having a need to read it in the future. Also, if making a hand-written entry, use good penmanship and write legibly. To some degree, the organization, comprehensiveness, and appearance of the aircraft logbooks have an impact on the value of the aircraft. High quality logbooks can mean a higher value for the aircraft.
Always use a checklist when performing an inspection. The checklist may be of your own design, one provided by the manufacturer of the equipment being inspected, or one obtained from some other source. The checklist should include the following:
- Fuselage and Hull Group
- Fabric and skin—for deterioration, distortion, other evidence of failure, and defective or insecure attachment of fittings.
- Systems and components—for proper installation, apparent defects, and satisfactory operation.
- Envelope gas bags, ballast tanks, and related parts—for condition.
- Cabin and Cockpit Group
- General—for cleanliness and loose equipment that needs to be secured.
- Seats and safety belts—for condition and security.
- Windows and windshields—for deterioration and breakage.
- Instruments—for condition, mounting, marking, and (where practicable) for proper operation.
- Flight and engine controls—for proper installation and operation.
- Batteries—for proper installation and charge.
- All systems—for proper installation, general condition, apparent defects, and security of attachment.
- Engine and Nacelle Group
- Engine section—for visual evidence of excessive oil, fuel, hydraulic leaks, and sources of such leaks.
- Studs and nuts—for proper torquing and obvious defects.
- Internal engine—for cylinder compression and for metal particles or foreign matter on screens and sump drain plugs. If cylinder compression is weak, check for improper internal condition and improper internal tolerances.
- Engine mount—for cracks and looseness of mounting.
- Flexible vibration dampeners—for condition and deterioration.
- Engine controls—for defects, proper travel, and proper safetying.
- Lines, hoses, and clamps—for leaks, condition, and looseness.
- Exhaust stacks—for cracks, defects, and proper attachment.
- Accessories—for apparent defects in security of mounting.
- All systems—for proper installation, general condition defects, and secure attachment.
- Cowling—for cracks and defects.
- Ground run-up and functional check—check all powerplant controls and systems for correct response, all instruments for proper operation and indication.
- Landing Gear Group
- All units—for condition and security of attachment.
- Shock absorbing devices—for proper oleo fluid level.
- Linkage, trusses, and members—for undue or excessive wear, fatigue, and distortion.
- Retracting and locking mechanism—for proper operation.
- Hydraulic lines—for leakage.
- Electrical system—for chafing and proper operation of switches.
- Wheels—for cracks, defects, and condition of bearings.
- Tires—for wear and cuts.
- Brakes—for proper adjustment.
- Floats and skis—for security of attachment and obvious defects.
- Wing and Center Section
- All components—for condition and security.
- Fabric and skin—for deterioration, distortion, other evidence of failure, and security of attachment.
- Internal structure (spars, ribs, compression members)—for cracks, bends, and security.
- Movable surfaces—for damage or obvious defects, unsatisfactory fabric or skin attachment, and proper travel.
- Control mechanism—for freedom of movement, alignment, and security.
- Control cables—for proper tension, fraying, wear, and proper routing through fairleads and pulleys.
- Empennage Group
- Fixed surfaces—for damage or obvious defects, loose fasteners, and security of attachment.
- Movable control surfaces—for damage or obvious defects, loose fasteners, loose fabric, or skin distortion.
- Fabric or skin—for abrasion, tears, cuts, defects, distortion, and deterioration.
- Propeller Group
- Propeller assembly—for cracks, nicks, bends, and oil leakage.
- Bolts—for proper torquing and safe tying.
- Anti-icing devices—for proper operation and obvious defects.
- Control mechanisms—for proper operation, secure mounting, and travel.
- Communication and Navigation Group
- Radio and electronic equipment—for proper installation and secure mounting.
- Wiring and conduits—for proper routing, secure mounting, and obvious defects.
- Bonding and shielding—for proper installation and condition.
- Antennas—for condition, secure mounting, and proper operation.
- Emergency and first aid equipment—for general condition and proper stowage.
- Parachutes, life rafts, flares, and so forth—inspect in accordance with the manufacturer’s recommendations.
- Autopilot system—for general condition, security of attachment, and proper operation.