High Maintenance

According to the FAA, the registered owner or the operator of an airplane is responsible for maintaining his airplane in an airworthy condition, including compliance with all applicable airworthiness directives (ADs), assuring that the maintenance is properly recorded and keeping abreast of current regulations concerning the operation and maintenance of his airplane.

The FAA has spelled out a number of inspections, maintenance procedures and checks that have to be completed in order for an airplane to be legal to lift off or to be used under instrument flight rules. Being legal and safe are not necessarily synonymous.

Every airplane is required to undergo an annual inspection. According to the FAA, "no person may operate an aircraft unless, within the preceding 12 calendar months, it has had an annual inspection and [has been] approved for return to service." A period of 12 calendar months extends from any day of a month to the last day of the same month the following year. Many owners schedule their inspections toward the end of a month so their airplane can be signed off and returned to service early in the next month; essentially creating a "13-month annual." That way they can spread the cost of the annual over 13 months instead of 12. Other owners stop their annual's forward progression in the middle of the winter so in the future they won't have any downtime during the flying season.

The details of an annual inspection are spelled out in the manufacturer maintenance manual and include the instructions for continued airworthiness, which address inspection intervals, parts replacement and life-limited components.

There are two exceptions to the annual inspection rule. Aircraft used to carry persons for hire or in which flight instruction is performed are required, within the preceding 100 hours of time in service, to have received either an annual inspection or a 100-hour inspection and approval for return to service. (Note that the rule applying to airplanes used for flight instruction does not require any compensation be exchanged.) The FAA recognizes that some operators may have scheduling problems for a 100-hour inspection, so it allows the 100-hour limitation to be exceeded by not more than 10 hours while en route to reach a place where the inspection can be done. There is a catch, though. The excess time must be included in computing the next 100 hours of time in service.

The other exception to an annual inspection is an approved progressive inspection program. A progressive inspection system can be set up to provide for a total inspection of the airplane on the basis of calendar time, time in service, number of system operations or a combination.

While the annual (or 100-hour) inspection is the most significant scheduled maintenance event, there are several others required in order for an airplane to be airworthy. The static pressure system, each altimeter instrument and each automatic pressure reporting system have to have been tested and inspected within the preceding 24 calendar months in order for the airplane to be operated in controlled airspace under instrument flight rules. The 24-month interval also applies to our transponders.

Another periodic requirement for instrument flight involves confirming that your VORs are sufficiently accurate. The regs state: "No person may operate a civil aircraft under IFR using the VOR system of radio navigation unless the VOR equipment of that aircraft is maintained, checked and inspected under an approved procedure, or has been operationally checked within the preceding 30 days and was found to be within the limits of the permissible indicated bearing error." This is probably one task that a number of pilots have been neglecting with the proliferation of GPS navigators.

There are several approved methods for conducting an operational check of a VOR. The most accurate check is to use an FAA-operated and -approved test signal or one radiated by a certificated and appropriately rated radio repair station or a point on an airport surface designated as a VOR system checkpoint. The maximum permissible indicated bearing error is plus or minus four degrees.

In addition to the ground-bound checks, there are a couple ways to check a VOR in the air. You can use an airborne checkpoint designated by the administrator: maximum permissible error is plus or minus six degrees. Or you can create an airborne checkpoint of your own by selecting a VOR radial that lies along the centerline of an established airway, select a prominent ground point along that radial, preferably more than 20 nm from the VOR ground facility, maneuver directly over the ground point at a reasonably low altitude and note the VOR bearing. The maximum permissible variation between the published radial and the indicated bearing is six degrees.

If you have dual VORs (independent except for antenna), you can check one system against the other. With both tuned to the same VOR you note the indicated bearings to the station; the maximum permissible variation between the two indicated bearings is four degrees.

Doing the check isn't the end of your responsibility. The rules require that "each person making the VOR operational check shall enter the date, place, bearing error and sign the aircraft log or other record." The rules haven't reflected the accuracy that GPS navigators now offer and don't allow a VOR to be checked against the GPS. If the VOR indication is within four degrees of the GPS that should be sufficient. But not legally.

All airplanes are required to have an emergency locator transmitter (ELT) in operable condition. To be sure an ELT is "operable" we're required to have it inspected within 12 calendar months after the last inspection for proper installation, condition and battery corrosion. But to be sure the batteries have the staying power in an emergency the FAA requires the batteries be replaced or recharged whenever the ELT has been in use for more than one cumulative hour or when 50 percent of their useful life has expired. The expiration date for replacing or recharging should be marked on the outside of the ELT and entered in the airplane's maintenance record.

Many of the 12- and 24-month inspections are typically performed during an annual inspection but not necessarily. As the owner-or the operator-it's technically your responsibility to be sure that the airplane you're flying has been properly inspected and returned to service.

And therein lies another potential "gotcha." An often overlooked regulation involves the requirement for a test flight to be conducted in some situations after a mechanic has been intimate with your airplane. According to the regs, "No person may carry any person in an aircraft that has been maintained, rebuilt or altered in a manner that may have appreciably changed its flight characteristics or substantially affected its operation in flight until an appropriately rated pilot with at least a private pilot certificate flies the aircraft, makes an operational check of the maintenance performed or alteration made and logs the flight in the aircraft records."

The qualifying words (appreciably and substantially) may leave some question about what requires a test flight. The rule does allow some wiggle room, by adding, "The aircraft does not have to be flown if, prior to flight, ground tests, inspections or both show conclusively that the maintenance, preventive maintenance, rebuilding or alteration has not appreciably affected the operation of the aircraft." The qualifier here is: "conclusively."

No matter what work has been accomplished, it behooves the prudent pilot to conduct a very, very thorough preflight and run-up before the airplane is returned to the sky. A pilot recently took off from King County International Airport in Seattle, Washington, in a Cessna Cardinal on what was described as a post-maintenance test flight. According to the National Transportation Safety Board, the pilot reported that just after liftoff, the aircraft started rolling to the left. He applied corrective right aileron, but that resulted in the roll to the left becoming accelerated. As the aircraft approached 80 degrees of bank, the left wing contacted the surface and the aircraft cartwheeled into the ground.

The flight was the first one after a replacement set of wings had been installed, and the FAA investigator determined the aileron control cables had been rigged so the airplane rolled opposite the pilot's inputs. The pilot said he had performed a pre-takeoff check of the aileron movement but did not realize that they deflected in a direction opposite to his inputs. The pilot was not injured, but his passenger received minor injuries.

There's one piece of mail that airplane owners dread finding in their mailboxes. The familiar appearance of an Airworthiness Directive with the "Postage & Fees Paid" frank in one corner and the U.S. Department of Transportation return address in the other is enough to make a grown man cry. Airworthiness Directives (ADs) are issued by the FAA to correct an unsafe condition found in an aircraft, engine, propeller, rotor or component "when such conditions exist or are likely to exist or develop in other products of the same design." Once a potential problem is discovered, the FAA uses ADs to notify aircraft owners about the condition and what action is required to correct it.

ADs can range from simple-and inexpensive-corrective actions such as attaching a new placard to an airplane's panel or inserting a new page in the Pilot's Operating Handbook (POH) to replacing a crankshaft or changing the gears in the oil pump. An AD can require a one-time action or inspections at specific intervals.

ADs are the final rule and must be complied with in order for an airplane to continue to be airworthy; compliance with them is mandatory. There are two basic types of ADs: emergency ADs that have to be complied with before further flight of an airplane and those of a less urgent nature. If it's not an emergency AD, there is usually a time by which compliance has to occur. For example the AD that required the replacement of an aluminum oil pump impeller and shaft assembly allowed the compliance to occur "at next engine overhaul...at next oil pump removal or five years after the effective date of this AD, whichever occurs first." There was a rush to accomplish this AD before this July when the five years expired.

While slightly less traumatizing, there's another category of mail that's distressing to owners. Service bulletins or owner advisories are suggested actions that companies issue to owners of their equipment. Although the actions recommended by these advisories are not required, their importance should be given serious consideration. As our airplanes become senior citizens they're beginning to feel their age and are requiring more and more care because of years of use or neglect. While many service bulletins appear to be more an effort to fend off lawsuits than to prevent problems, attention should be paid.

Working with your mechanic, you can decide which service bulletins or owner advisories should be complied with and which can be postponed. Every time an airplane is opened for work, it's exposed to "opportunistic infections," so it's important to consider the relative value of the work before deciding to let someone lay hands upon your airplane. An effort to extend the annual from an annual to a biennial event because of the potential for introducing new problems every time the airplane is worked on hasn't yet succeeded in convincing the FAA that the extension would actually be safer by not introducing new problems.

But just as the flight physical can only guarantee an airman's health at the moment of the exam, an annual inspection of the airplane only verifies the airworthiness at the completion of the inspection. Between annuals the responsibility for assuring an airplane's airworthiness lies with the owner or operator.

Type clubs are an excellent source of information for helping pilots maintain their aging airplanes. I belong to a group called the Cardinal Flyers Online, and we have the luxury of two Cardinal experts who maintain and edit an e-mail "digest" that contains a thread of questions and suggestions from other Cardinal owners who have "been there, done that." If anyone has a question or problem, they're able to post a query, and responses are quick in coming back. For example, an owner's mechanic may have worked out a procedure to efficiently comply with an AD, and the solution is then shared with the rest of us. I've frequently passed on suggested solutions to maintenance technicians working on my airplane and, to their credit, most of them have readily accepted the "expert" advice in the spirit with which it was given.

The importance of maintaining an airplane in flying condition is obviously critical to safety. The fact that most accidents are caused by pilot error and not mechanical failures is a testament to how well our airplanes and their components are designed and built and how well they're being maintained. But as our airplanes mature and approach retirement, we're going to have to be more vigilant in watching for signs of deterioration and aging. Sagging cables, weakening hydraulic hoses and corrosion are becoming epidemic, and we're going to have to be more alert to our airplanes' complaints and old-age ailments. The FAA requirements-and properly documenting compliance with them-is a good start, but as pilots we have to be aware of the physical condition of the airplanes we're flying and if-and when-necessary check them into clinics to make them well again.