AD 99-21-31 ACTIVE

This amendment adopts a new airworthiness directive (AD), applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes, that requires removing the control quadrant, securing the power lever cam screws with Loctite, and reinstalling the control quadrant. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent the cam screws of the engine power levers from backing out and interfering with the movement of the engine power levers, which could result in limited engine power, and consequent reduced controllability of the airplane.

Final rule

99-21-31 SAAB AIRCRAFT AB: Amendment 39-11377. Docket 98-NM-244-AD. Issued October 8, 1999.
Applicability: Model SAAB SF340A and SAAB 340B series airplanes, as listed in Saab Service Bulletin 340-76-042, dated May 28, 1998, certificated in any category.

NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions toaddress it.

Compliance: Required as indicated, unless accomplished previously.

To prevent the cam screws of the engine power levers from backing out and interfering with the movement of the engine power levers, which could result in limited engine power, and consequent reduced controllability of the airplane, accomplish the following:

(a) Within 1,200 flight hours or 6 months after the effective date of this AD, whichever occurs first, remove the control quadrant, secure the power lever cam screws with Loctite, and reinstall the control quadrant, in accordance with Saab Service Bulletin 340-76-042, dated May 28, 1998, including Attachments 1, 2, and 3, all dated May 1, 1998.

(b) As of the effective date of this AD, no person shall install on any airplane any control quadrant unit having part number (P/N) 53082, 53162, or 53170, unless the control quadrant unit has been modified in accordance with this AD.

Alternative Methods of Compliance
(c) An alternativemethod of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

Special Flight Permits
(d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

Incorporation by Reference
(e) The actions shall be done in accordance with Saab Service Bulletin 340-76-042, dated May 28, 1998, including Attachment 1, dated May 1, 1998, Attachment 2, dated May 1, 1998, and Attachment 3, dated May 1, 1998, which contains the following list of effective pages:

Page Number
Revision Level
Shown on Page
Date Shown on Page
1-4
Original
May 28, 1998

Attachment 1

1-4
Original
May 1, 1998

Attachment 2

1-4
Original
May 1, 1998

Attachment 3

1-4
Original
May 1, 1998

This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Saab Aircraft AB, SAAB Aircraft Product Support, S-581.88, Link ping, Sweden. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

NOTE 3: The subject of this AD is addressed in Swedish airworthiness directive 1-128, dated May 29, 1998.

(f) This amendment becomes effectiveon November 24, 1999.

FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149.

A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes was published in the Federal Register on October 27, 1998 (63 FR 57260). That action proposed to require removing the control quadrant, securing the power lever cam screws with Loctite, and reinstalling the control quadrant.

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

Request to Withdraw Proposed AD
One commenter states that the proposed action (i.e., removal of all control quadrants to put Loctite on the screws) is not warranted for the following reasons:

1. The proposed rule is based on two events that occurred at a single operator. Investigation of these events showed that the migrated screw was an incorrect part number from the flight idle stop assembly. The commenter notes that no other operators have reported this problem, which indicates that the installation was an error in the field, and not a problem introduced during the modification of the control quadrant by its vendor (Adams-Rite). The commenter also states that an audit of related inventory, kits, and items in stock at the control quadrant vendor found no screws with incorrect part numbers, which further indicates that the problem was caused by a field installation error of the flight idle stop modification kit.

2. The commenter states that a check of it's spare throttle quadrants shows that the correct screws have been installed within the flight idle stop assembly and are installed tightly. There is no indication that these screws can migrate, or "back out" of place.

3. Given the amount of time and hours accrued since installation of the flight idle stop, the commenter states that any screws susceptible to such migration should already have shown signs of movement. The commenter further notes that a much simpler inspection would be to use a strong light and look through the power lever slot in the control quadrant to examine the screws, and only remove the quadrant if the screws show signs of looseness. An inspection interval of 200 flight hours would be sufficient until the quadrant was removed for other causes, which would allow accomplishment of the service bulletin (i.e., Saab Service Bulletin 340-76-042, dated May 28, 1998, including Attachments 1, 2, and 3, all dated May 1, 1998, was cited as the appropriate source of service information in this NPRM) at that time.

4. A test conducted at the control quadrant vendor showed that, in the worst-case, interference with the power levers caused by any migration of loose screws could be overcome by the flight crew using an additional 8 lbs of force. Therefore, the crew would not lose control of engine power.

The FAA does not concur with the commenter's statement that the proposed AD is not warranted. The FAA has determined that the actions required by this AD are appropriate for the reasons described below.

Although the commenter states that a single operator incorrectly installed the migrated screws, installation of any screws in the area affected by this AD would not have been accomplished by any operator, only by the vendor of the control quadrant. Additionally, the FAA has been advised that the two control quadrants that have had the problem were manufactured in different batches with a long period of time in between. The results of the audit at the control quadrant vendor do not adequately explain why incorrect screws were installed during manufacture of these two quadrants. Therefore, the FAA has determined that it is necessary to accomplish an inspection and modification of all quadrants.

The FAA also disagrees with the commenter's statement that it has determined that correct screws are installed inside its spare quadrants. Further discussions with Luftfartsverket (LFV), which is the airworthiness authority for Sweden, and Saab have revealed that it is not possible for operators to adequately check the installation of the correct screw length without disassembling the control quadrant. Further, such disassembly is only to be accomplished by the quadrant vendor.

The FAA also disagrees that the screws should already have migrated, or that they can be checked periodically for looseness. It may be possible for the screws to remain in place for some time due to friction below the head of the screw, and then suddenly become loose due to vibration. It is not possible to predict how quickly or when such an event would occur. A periodic inspection such as the commenter suggests would not adequately prevent the possibility of a sudden restriction of power lever movement.

Although the FAA does not disagree with the results of the test showing that 8 lbs. of force would overcome restriction of the power levers, the FAA does not concur that such action on the part of the flight crew is appropriate. Since the flight crew would not be aware of the cause of the sudden binding in the power levers, they would not reasonably be expected to know what action to take, how much force to apply, and when to stop applying the extra force.

Request for Revision of Cost Impact Information
One commenter requests that the FAA remove the sentence that reads "required parts would be supplied by the manufacturer at no cost to the operators" from the Cost Impact section of the proposed AD. The commenter notes that no parts are necessary to accomplish the modification, only consumables (i.e., Loctite and Loctite primer).

The FAA concurs with the commenter's request. The cost impact information, below, has been revised accordingly.

Conclusion
After careful review of the available data, including the comments noted above, the FAA has determined that air safety and the public interest require the adoption of the rule with the change described previously. The FAA has determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD.

Cost Impact
The FAA estimates that 283 airplanes of U.S. registry will be affected by this AD, that it will take approximately 9 work hours per airplane to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the cost impact of the AD on U.S. operators is estimated to be $152,820, or $540 per airplane.

The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted.

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 responsibilities among 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from 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 U.S.C. 106(g), 40113, 44701.

39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive:

The service information referenced in this AD may be obtained from Saab Aircraft AB, SAAB Aircraft Product Support, S-581.88, Linkoping, Sweden. This information may be examined at the Federal Aviation Administration (FAA), Transport Airplane Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Norman B. Martenson, Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2110; fax (425) 227-1149.