AD 96-19-18

Events Leading to This Action

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to certain Socata TBM 700 airplanes registered in the United States was published in the Federal Register on April 9, 1996 (61 FR 15738). The action proposed to require installing four rivets on the right side of the rudder and drilling drainage holes at the specified areas of the elevators and rudder. Accomplishment of the proposed installation as specified in the notice of proposed rulemaking (NPRM) would be in accordance with Socata Service Bulletin (SB) TBM 70- 027 and Socata SB TBM 70-028, both dated September 1993.

Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the four comments received from one commenter.

Comment Issue No. 1: Divide the Proposal Into Two Different AD's

Socata suggests that theactions specified by the NPRM would be clearer if they were broken out into two separate AD's. The reasons that Socata gives are:

o the Direction G n rale de l'Aviation Civile (DGAC), which is the airworthiness authority for France, issued two separate AD's;

o there are two separate Socata service bulletins: Socata SB TBM 70-027 and Socata SB TBM 70-028, both dated September 1993; and

o justification, causes, and effects of each action proposed in the NPRM are different.

The FAA concurs that the DGAC issued two separate AD's and that there are two service bulletins. However, the FAA does not concur that the justification, causes, and effects of each action proposed in the NPRM are entirely different. Socata SB TBM 70-027 requires installing four rivets on the rudder. If this is not accomplished and debonding occurs, then moisture can accumulate in the rudder. Thus, Socata SB TBM 70-028 contains procedures for drilling drainage holes in the elevator and rudder to reduce corrosion effects caused by moisture accumulation that could lead to control surface imbalance. The FAA has determined that one AD is justified because accomplishment of the actions specified in both service bulletins will help prevent control surface imbalance and the compliance times are exactly the same (thus preventing the owner/operator from having to schedule the accomplishment of two separate AD actions). No changes have been made to the AD as a result of this comment.

Comment Issue No. 2: Need More Justification for Stating That the Existing Conditions Could Cause Loss of Control of the Airplane.

Socata states that, if the FAA believes that the conditions specified in the NPRM, ". . . if not detected and corrected, could result in loss of control of the airplane", then the FAA should be more precise in stating how this is correct. Also, concerning the bonding defect between the skin and the rear spar (Socata SB TBM 70-027), Socata states that loss of control of the airplane is improbable with the assumption that the safe life of the rudder will be affected over time without corrective action.

The FAA believes that the conditions, if not detected and corrected, could result in loss of control of the airplane. The objective of Socata SB 70-028 is to provide control surface drainage (elevator and rudder). Moisture that accumulates in the control surfaces can freeze when the aircraft climbs to a high altitude, which then could result in control surface imbalance. This effect can cause flutter, which can result in loss of control of the airplane. As earlier explained (Comment Issue No. 1), the accomplishment of the actions specified in both Socata SB TBM 70-027 and Socata SB TBM 70-028 will help prevent these control surface imbalances. No changes to the AD have been made as a result of this comment.

Comment Issue No. 3: Problems With the Absence of Elevator and Rudder Drainage Holes

Socata states that different problems could occur with the absence of drainage holes in the elevator and rudder. These problems are:

"- Corrosion for airplanes which could stay at parking for a long time where water would stagnate,

- if the water freezes, it may slightly affect the controls balance."

No specific changes to the AD or recommendations for additional or different AD action were presented by the commenter regarding this issue. No changes to the AD have been made as a result of this comment.

Comment Issue No. 4: Workhours for Accomplishing Actions are Incorrect

Socata states that the workhours for accomplishing the actions specified in the NPRM are incorrect. For example:

- For installing the rivets, one workhour is required instead of two as specified in the NPRM; and

- For drilling the drainage holes, 1.5 hours is needed instead of two as specified in the NPRM.

The FAA concurs. However, FAA policy is to round fractional numbers concerning workhours to the next whole number. Therefore, the workhours for installing rivets will be changed in the AD to reflect 1 workhour; however, the workhours for drilling the drainage holes will remain at 2 workhours.

The FAA's Determination

After careful review of all available information related to the subject presented above, including the referenced service information, the FAA has determined that air safety and the public interest require the adoption of the rule as proposed except for the change to the economic information and minor editorial corrections. The FAA has determined that the change and minor corrections will not change the meaning of the AD and will not add any additional burden upon the public than was already proposed.

Cost Impact

The FAA estimates that 31 airplanes in the U.S. registry will be affected by the required rivet installation and 35 airplanes will be affected by the required drainage hole drillings, that it will take 1 workhour to install the rivets and 2workhours to drill the drainage holes, and that the average labor cost is $60 per hour. No cost is attributed to parts that would be necessary to accomplish the required actions since these parts are available through common operator stock and an approximate cost cannot be traced. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $1,860 or $60 per airplane for the rivet installation and $4,200 or $120 per airplane for the drainage hole drilling. Since parts are not sold through the manufacturer, the FAA has no method of determining the number of parts already distributed, and thus bases this cost impact upon the assumption that no owner/operator of the affected airplanes has accomplished the required actions.

Regulatory Impact

The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilitiesamong the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the final evaluation prepared for this action is contained in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption "ADDRESSES".

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. Adoption of the Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: PART 39 - AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 USC 106(g), 40113, 44701. Section 39.13 - [AMENDED] 2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: