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Mooney aileron link AD petitionMooney aileron link AD petition

Federal Aviation Administration, Central Region
Office of the Chief Counsel, Room 1558
Attn: Rules Docket No. 98-CE-20-AD
601 E. 12th Street
Kansas City, MO 64106


The Aircraft Owners and Pilots Association (AOPA), representing the aviation interests of more than 340,000 pilots and aircraft owners, submits the following petition for reconsideration of an airworthiness directive (AD) pursuant to 14 C.F.R. § 11.93. On November 23, 1998, the Federal Aviation Administration (FAA) published AD 98-24-11 in the Federal Register. This AD requires initial and repetitive inspections, modification, or replacement of the aileron control links on certain Mooney Aircraft Corporation M20-series aircraft. Since the issuance of this final rule, AOPA has become aware of service data demonstrating that this AD should be significantly modified in the interests of reducing the economic and operational burden on the approximately 7,500 owners impacted by this AD.

Over the past 30 days, AOPA has been assisted in gathering service data on the aileron control links by a group of affected aircraft owners and a number of maintenance facilities specializing in the inspection and repair of Mooney aircraft. The service data is based on the prior conduct of inspections or replacement/modification of the aileron links in accordance with Mooney Engineering Design Service Bulletin (SB) No. M20-164. To date, AOPA is directly aware of approximately 350 aircraft that have been inspected in the United States and Australia. Of these, there have been three reports of cracked aileron control links at the angle joint. Each of these cracks was detected visually prior to removal from the aircraft. In addition, it has been brought to our attention that Lake Aero Styling & Repair has modified approximately 750 sets of aileron control links to date, during which time only two links were found to be cracked. AOPA is not clear whether these two cracks are in addition to, or included in, the three previously mentioned cracks found in the field. Most importantly, however, the cracks found at Lake Aero Styling & Repair were also reportedly found by visual inspection. AOPA is continuing to gather additional service data as of this writing.

Based on the results of nearly 1,100 initial inspections conducted to date, AOPA maintains that the initial and repetitive off-wing magnetic particle inspection should be removed from this AD and replaced with an on-wing visual inspection. As demonstrated above, extensive field experience has shown that very few aileron links have been found cracked. The handful of cracks that were found have all been detected by visual means. Further, AOPA has learned that Lake Aero Styling & Repair has rejected as many aileron links due to damage inflicted during removal from the aircraft as they have for the presence of cracks in the angle joint. This indicates to us that repetitive removal of the links from the aircraft for a magnetic particle inspection could create additional unforeseen airworthiness concerns and unnecessarily subject owners to the cost burdens of replacing otherwise airworthy aileron control links. For these reasons, AOPA maintains that the initial and repetitive off-wing magnetic particle inspection should be replaced immediately by an initial and repetitive on-wing visual inspection.

As a rule, AOPA maintains that airworthiness directives should include some form of terminating action. We believe this because often the conduct of repetitive inspections can be very burdensome to the aircraft owner because of having to remove the aircraft from service at odd intervals. In this instance, the FAA has provided a terminating action to the repetitive inspection regimen by replacing the original aileron control links with new parts from Mooney Aircraft Corporation or modified parts from Lake Aero Styling & Repair under their Part Manufacturing Authority. There has been a very low incidence of actual cracks being detected on the aileron control links, and most of these could be traced to aircraft damage history. Therefore, AOPA believes it is entirely appropriate to maintain a repetitive visual inspection interval as an alternative to part replacement or modification for those owners who do not wish to incur the cost and inconvenience.

While we agree that a repetitive visual inspection would be prudent for those aircraft that have not been modified, AOPA believes that inspection interval should be changed to “each annual inspection after initial compliance.” Access is normally gained to the aileron control links at each annual inspection for the purposes of inspecting and lubricating the Heim bearing and other associated components. Most Mooney M20 aircraft are privately owned and thus are not subject to the 100-hour inspection intervals required of commercial operators. By aligning a repetitive on-wing visual inspection of the control links with the annual inspection, the FAA would save operators the expense and inconvenience of having to remove the aircraft from service and gain access to the links for a dedicated inspection. This cost makes up the bulk of the expenses associated with any visual inspection.

In our view, changing the compliance time for the repetitive visual inspection to the annual inspection would not degrade current safety levels. This is due to the fact that the vast majority of privately owned general aviation aircraft fly far fewer than 100 hours each year. In fact, by requiring a visual inspection of the aileron control links at the annual inspection, the majority of aircraft would actually be inspected more often than is currently required by the by AD 98-24-11. While this is potentially a positive safety enhancement, there would be no increase in cost to the aircraft owner since access is already gained to the control links during the course of the normal annual inspection.

In summary, based upon the service data gathered to date, AOPA believes that both the method and interval of compliance with AD 98-24-11 should be changed. The existing initial and repetitive 100-hour off-wing magnetic particle inspection of the aileron control links should be changed to an initial and repetitive annual visual inspection. These changes would bring about significant cost savings to the approximately 7,500 owners affected by this AD and should not degrade safety in any manner.

We thank you for your time and consideration in this matter and stand ready to assist the FAA in reconsidering this airworthiness directive.


Douglas C. Macnair
Certification and Regulatory Policy

December 22, 1998

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