Airframe and Powerplant

Information Central

October 1, 2005

How FAA information helps owners

Airplane owners who take an interest in the full scope of ownership — not just in the piloting skills required to plan and complete their flights — learn that the real struggle involved in ownership boils down to information. There's no shortage — it seems as if everyone even remotely involved in aviation fancies himself an expert on some subject and is willing to share his expertise. It's learning to separate the wheat from the chaff that takes time.

When I started flying in a Cessna 150 I was told to never touch the mixture control below 5,000 feet msl. No one explained why nor did I ask. Later I began asking questions. As time went by, more information came my way — information that explained why and when engines are leaned, and why they should be leaned. This ongoing process of discovery relating to everything aeronautical is part of the fun of aviation, but it does require a large time investment.

The Internet has given owners access to a staggering blizzard of information. Some of this blizzard is pure opinion unsupported by fact or science, while some of it contains nuggets of pure gold. One place that does contain data based on fact is the FAA's special airworthiness information bulletin (SAIB) Web site ( www.faa.gov/aircraft/safety/alerts).

Everything from soup to nuts

The SAIB Web site is a clearinghouse of free aeronautical information, which can only be described as wide ranging and extremely varied. Want the lowdown about a wing problem in one model of a well-known homebuilt design? Visit the SAIB Web site.

Want to get information on the perils of using a cork gasket between a vacuum pump and the engine? Visit the SAIB Web site.

Want approved data to replace those hard-to-drive solid rivets with much easier installed threaded fasteners when replacing Cessna seat rails? Visit the SAIB Web site.

There's an SAIB that directs owners of Diamond DA20-C1 airplanes with TCM IO-240 engines to a Teledyne Continental Motors service bulletin, which addresses engine-idle stability problems. There's also an SAIB that addresses faulty engine maintenance in both Lycoming and TCM reciprocating engines. The Cessna Pilots Association Web site ( www.cessna.org) has a list of more than 40 SAIBs that apply to Cessna singles or twins in some manner or another.

Precursors to an AD?

According to the FAA, the airworthiness directives (ADs) process is designed to correct an unsafe condition. ADs are regulatory — they're law and they must be complied with in the appropriate manner. SAIBs are not regulatory — they're written and issued as informational tools designed to alert, educate, and make recommendations to the aviation community.

The SAIB program was created by the airworthiness branch (AIR) of the FAA. The first SAIB was issued in October 1994 — it applied to Lockheed C130A- and C130B-model airplanes. This SAIB contained inspection suggestions to detect and prevent engine nacelle fires that were suspected as the cause of an in-flight wing failure of a firefighting 130A. The following sentence from that first SAIB explains one advantage of SAIBs — they can be written and issued much quicker than an AD: "Dissemination of this information at this time is intended to be a preventive measure; it does not preclude the possibility of the issuance of mandatory action subsequent to the outcome of the accident investigation."

The second SAIB issued that year — a total of six were issued between October 1994 and the following September — alerted the operators of Bell 204- and 205-model helicopters that the tail rotor gearboxes were failing because of repeated heavy-load lifting operations. As in the first SAIB, there's a clarifying sentence, which reads: "The FAA anticipates that an airworthiness directive (AD) will be issued when all the test data has been received from BHTI [Bell Helicopter Textron Inc.] and approved. In the meantime, awareness and education are the only means of reducing the frequency of accidents because of the gearbox failure. This special airworthiness information was developed as an interim measure to aid in achieving that goal."

Does this mean that the issuance of an SAIB is always followed by an AD? Not at all. As the SAIB program has grown in the past decade, aerospace engineers working out of flight standards district offices (FSDOs) from Albany to Anchorage and Fargo to Fort Lauderdale have started writing more SAIBs. Since those early days, the volume of SAIBs and the breadth and scope of the subjects covered by them have expanded considerably. The program continues to grow.

Within two years of the program's inception, aerospace engineers were generating so many SAIBs that the year was divided into two six-month periods. The break was required to maintain a manageable number of 25 SAIBs per calendar period, but this number is fluid, varying from a low of 17 from October 1998 through March 1999 to a high of 28 in the time from April 2002 through September 2002. The volume had increased so much by the end of summer 2002 that the release period was reduced again — from that point until today the SAIB catalog has been divided into three-month periods.

747s to 120s and tires to tail cones

The SAIB Web site is a treasure trove of airplane information. The information in the bulletins ranges from large items such as Pratt & Whitney JT9D turbofan engines — four of these engines power Boeing's amazing 747 — to the fuel caps on a Cessna 120. Operational topics also are covered. A recent SAIB echoes a Parker Hannifin mailing that explains the hazards of single-pneumatic-source IFR operations and makes a number of recommendations to increase safety and redundancy (Parker Hannifin produced dry-air pneumatic system pumps for years before selling off its entire pump operation a few years ago).

SAIBs notify owners of the existence of alternate methods of compliance (AMOCs) for airworthiness directives. For example, a 1998 SAIB notified owners of an easier method to comply with a 1998 AD calling for the compression crack inspections in the wing spars of American Champion 8GCBC Scout airplanes.

There's an SAIB alerting the users of a particular brand of super-large tundra tires that some of these tires were not built to appropriate standards. The suggested action reads: "We recommend that these tires be weighed within 100 landings after the receipt of this SAIB. If the tires don't weigh enough, that's sufficient proof that they're part of the non-standard batch."

Mary Ellen Anderson is the FAA Information Program manager for the SAIB program. "SAIBs are a tool that the aircraft certification side of the FAA uses to get information out to owners. Before the SAIB program there never was a formal policy or mechanism for this kind of information. These bulletins may defuse the need to create regulatory guidance," she says.

If it sounds like SAIBs are used to alert owners and owners groups of the FAA's concern on certain issues — and give the owners groups a chance to create a response to the issue that's satisfactory to the FAA before the issue becomes serious enough to merit an AD — that's what it should sound like.

The Comanche SAIB

On September 15, 2004, an SAIB was issued and mailed to the registered owners of Piper airplanes with stabilators. These Piper models do not have horizontal stabilizers and elevators — pitch control is maintained by changing the angle of the entire stabilator. The SAIB alerted owners to the possibility of corrosion of the stabilator torque tube, attaching fittings, and attaching fasteners.

The stabilator torque tube projects out of the left and right sides of the aft fuselage — it's supported on each side by roller-type bearings. The left and right stabilator halves are installed by sliding them over the steel torque tube and locking them into position by inserting two close-tolerance bolts. An AD from the mid-1970s required owners of stabilator-equipped airplanes to replace the original steel close-tolerance bolts with close-tolerance stainless-steel bolts. The concern of the SAIB is that compliance with the AD may have compromised the corrosion protection of the torque tube.

The Piper factory did a good job taking steps to reduce the possibility of torque-tube corrosion by electroplating the outer surface of the steel torque tube with a thin coat of cadmium. Two coats of paint were applied to the inner surface — zinc chromate was flushed through, then was followed by a swab coat of enamel.

The SAIB included color pictures of a severely corroded torque tube and recommended that owners remove the left and right stabilators within 100 hours to check for corrosion of the torque tube, attaching fittings, and attaching fasteners. The SAIB requested that owners notify the originating certification office if damage was found.

The ICS — a proactive stance

The International Comanche Society (ICS) is an owners group that provides informational, social, and advocacy services for its members. For years, Maurice Taylor, a retired Piper employee, provided technical expertise to ICS members. After many years of service Taylor died last year. To fill the void left by Taylor's passing, a 12-member technical committee was formed. Members of this committee take SAIBs seriously.

Hans Neubert is one of those members. "We treated [the Piper SAIB] as a heads-up," says Neubert. "We think the FAA is saying, 'Deal with it in your own way, in your own manner, but deal with it,'" referring to the torque-tube-corrosion problem in this case. "We think they're telling type clubs to get into action to deal with aging-aircraft issues before they [the FAA] have to," says Neubert.

In cooperation with the FAA Aircraft Certification Office (ACO), which wrote the SAIB, the ICS obtained the corroded torque tube that prompted the SAIB and is conducting tests — Neubert holds a designated engineering representative endorsement from the FAA — to determine whether the corrosion has compromised the torque tube to the point of it no longer being airworthy.

The test methodology and data will be submitted to the ACO along with testimony from owners about the results of their individual corrosion inspections. In addition, the technical committee has queried 11 maintenance shops that are known to be Comanche savvy and submitted comments on the torque-tube-corrosion issue. This body of evidence will help form a more comprehensive picture of the extent of the problem, and recommendations from ICS will have weight in determining if further action is required.

The same kinds of tests are taking place in other type groups as they address their own sets of aging-aircraft problems. The SAIB program gives owners a chance to get involved in determining the airworthiness of their airplanes, and in helping formulate methods for maintaining airworthiness in the future. To receive SAIBs that apply to your airplane, keep your airplane registration information current ( www.faa.gov/aircraft/air_cert/aircraft_registry). If you or someone you know would like to get involved in responding to aging-aircraft issues, or have professional qualifications that will aid the cause of maintaining airworthiness in aging GA airplanes, contact your aircraft type club. A list of association and type groups with contact information is available on AOPA Online ( www.aopa.org/members/associations/).


E-mail the author at steve.ells@aopa.org.