[Federal Register Volume 64, Number 202 (Wednesday, October 20, 1999)]
[Rules and Regulations]
[Pages 56426-56428]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-26935]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 98-NM-244-AD; Amendment 39-11377; AD 99-21-31]
RIN 2120-AA64
Airworthiness Directives; Saab Model SAAB SF340A and SAAB 340B
Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: 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.
DATES: Effective November 24, 1999.
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of November 24, 1999.
ADDRESSES: 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.
FOR FURTHER INFORMATION CONTACT: Norman B. Martenson, Manager,
International Branch, ANM-116, FAA, Transport Airplane Directorate,
1601
[[Page 56427]]
Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-
2110; fax (425) 227-1149.
SUPPLEMENTARY INFORMATION: 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
[[Page 56428]]
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.
Sec. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new
airworthiness directive:
99-21-31 SAAB AIRCRAFT AB: Amendment 39-11377. Docket 98-NM-244-AD.
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 to
address 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 alternative method 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
Secs. 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:
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Revision level shown on
Page Nos. page Date shown on page
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1-4................. Original............... May 28, 1998.
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Attachment 1
1-4................. Original............... May 1, 1998.
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Attachment 2
1-4................. Original............... May 1, 1998.
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Attachment 3
1-4................. Original............... May 1, 1998.
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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, Linkoping, 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 effective on November 24, 1999.
Issued in Renton, Washington, on October 8, 1999.
D.L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 99-26935 Filed 10-19-99; 8:45 am]
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