By Leslie Caubble, CFI/IGI
How do you know that the aircraft you’re flying is properly maintained? Quality maintenance is vital to safe operation of an aircraft. Unlike an automobile maintenance break down, you can’t pull over to the side of the road! The FAA mandates a minimum number of maintenance checks and inspections to be performed to assure that aircraft are functioning to standards and safe for passengers.
Passenger safety is paramount to the FAA, so routine checks and inspections are mandatory. Every airline/operator must establish a Continuous Airworthiness Maintenance Program (CAMP). A CAMP is a plan established to guarantee an aircraft remains airworthy through the life of service by adhering to maintenance and preventative maintenance checks. These routine checks are highly regulated by the FAA and designed to ensure passengers can safely travel to and from their destinations.
There are also required inspections for civil aircraft. The list of inspections gets longer if the aircraft is for compensation/for hire, or if flown under instrument flight rules (IFR). Knowledge of these inspections is a required element to pass a checkride.
Let’s break down ten different types of checks and inspections for commercial and civil aviation:
Commercial Aviation Operations
Any aircraft operating under Part 121, Part 135, and some Part 91k (fractional ownership) must establish a Continuous Airworthiness Maintenance Program (CAMP). These programs outline the routine and non-routine maintenance checks for each aircraft in operation. Some inspections, repairs, and replacements are required after a certain time (flight hours) in service or after a specified calendar time.
Think about a routine oil change on your car: Depending on your make/model, your next oil change might be due in 3 months or 3,000 miles, whichever comes first. Some of these same principles apply to the required maintenance checks.
1) Line Maintenance Checks
Line maintenance checks are the inspections that are performed most routinely. Most of these checks can even be done as the airplane is sitting at the gate because they are minimally invasive, require less tools, and take fewer maintenance personnel. Depending on the maintenance specifications required by the FAA for that airplane, these checks commonly happen after 24-60 hours of flight time.
Some of the things that are inspected during a line maintenance check are:
- Brakes
- Tires
- Hydraulics
- Oil level
2) A Checks
Depending on the operation, A Checks are typically performed between 400-600 flight hours, or every 200-300 flights. These checks take a full working day, so the aircraft is usually parked inside of a hangar. Unless discrepancies are found, the aircraft can be returned to service in as little as 10-12 hours.
Some of the A Checks include:
- Lubrication of key systems
- Corrosion prevention
- Checking emergency equipment
“B Checks” have been phased out of maintenance programs, and the tasks are usually rolled into the A Checks to minimize downtime. These additional checks can include checking alignment, wheel wells, and inspecting for fluid leaks.
3) C Checks
C Checks are more extensive than A/B Checks and are considered heavy maintenance. Depending on the work done, the aircraft can be offline for 1-2 weeks. C Checks are a more in-depth inspection of the complete aircraft. These checks require many more man hours, tools, hangar space, and aircraft downtime. When a plane is down for C Checks, it can take up to 6,000 technician hours to get the complete inspection done.
4) D Checks
Finally, D Checks are the most exhaustive type of maintenance checks for commercial aircraft. These checks happen every 6-10 years and include a full dismantling of the aircraft to thoroughly inspect every component for corrosion and damage. D Checks can take 30,000-50,000 technician hours to complete. D Checks require so much time, manpower, and money to perform that these need to be scheduled years in advance.
Civil Aviation Operations
The FAA also mandates several inspections to be performed at regular intervals on civilian aircraft. It is the responsibility of the owner/operator to ensure these inspections are completed and documented. It’s the responsibility of the pilot-in-command (PIC) to confirm that the inspections have been performed and the aircraft airworthy before conducting a flight. These required inspections are vitally important to the safe operation of general aviation aircraft, so even student pilots are required to know the basics to pass a Private Pilot checkride.
Aviation is full of helpful mnemonics and acronyms, and there is a great memory aid available for these required inspections: AV1ATE
A: ANNUAL INSPECTION (FAR 91.409)
An annual inspection must be completed within the previous 12 calendar months for an aircraft to be airworthy. The inspection must be endorsed by a mechanic who holds an additional certification called an Inspection Authorization (IA). If the aircraft doesn’t have “the annual” performed and signed off within 12 calendar months, it is grounded until completed. There are a few exceptions when the aircraft can be flown outside of this timeframe, such as when a special flight permit is issued.
V: VOR INSPECTION (FAR 91.171)
For any flight operated under instrument flight rules (IFR) using a VOR navigation system, the VOR must be routinely checked/maintained, and an operational check performed within the previous 30 days. There are several ways the VOR can be tested for accuracy of operation, and the results can be performed and logged in an aircraft log by the pilot.
1: 100 HOUR INSPECTION (FAR 91.409)
If the aircraft is operated for compensation or hire, including flight training, it must complete an inspection within the previous 100 hours of operation (engine tach time). The “100 hour inspection” is very similar to the annual inspection of the airframe, powerplant, and propeller. One major difference is that any A&P technician can endorse the inspection.
A: ALTIMETER/PILOT STATIC INSPECTION (FAR 91.411)
If flying under IFR, an aircraft’s static system, altimeter and automatic Mode C altitude-reporting system must be inspected within the preceding 24 calendar months.
T: TRANSPONDER INSPECTION (FAR 91.413)
The transponder also must be inspected every 24 calendar months, even for flight under VFR (visual flight rules). You may notice, especially at flight schools, that your airplane will have the altimeter, static system, and transponder inspected on the same day, even if the plane doesn’t usually fly under IFR. That’s because typically the same avionics technician can perform all of these at the same time, at the same interval, with little additional cost to the owner/operator.
E: ELT INSPECTION (FAR 91.207)
Finally, every civil aircraft must have an Emergency Locator Transmitter (ELT) which must be inspected every 12 calendar months. This is to ensure the ELT is properly installed, battery operational, and has enough signal strength. You may notice the inspection date falls in line with the Annual inspection, since both are required at 12 calendar month intervals.
Not only do aviation maintenance checks and inspections keep the flying public safe, they can also help prevent major repairs down the road if discrepancies are found early. Potential problems can be addressed, and any wear and tear that could compromise safety can be repaired. Whatever aircraft you’re flying, take the time to verify these important checks in the aircraft maintenance logs. Your safety, and even your pilot certificate, could be on the line.
By Leslie Caubble, CFI/IGI
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