[Federal Register Volume 64, Number 147 (Monday, August 2, 1999)]
[Rules and Regulations]
[Pages 41778-41780]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-19297]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 98-NM-372-AD; Amendment 39-11238; AD 99-16-03]
RIN 2120-AA64


Airworthiness Directives; Learjet Model 23, 24, 25, 28, 29, 31, 
55, and 60 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 Learjet Model 23, 24, 25, 28, 29, 31, 55, and 60 
series airplanes, that requires a one-time detailed visual inspection 
of the electrical wire leads of the horizontal stabilizer anti-ice 
system to verify that the numbers on the wire leads correctly 
correspond to the numbers on the connected airframe wiring; 
installation of a wire ID strap on the left-and right-hand sides of 
each terminal block; and installation of a warning placard. This 
amendment is prompted by a report of severe flight control buffeting of 
a Learjet Model 55 series airplane due to a malfunction of the 
horizontal stabilizer anti-ice system. The actions specified by this AD 
are intended to prevent undetected accretion of ice on the leading edge 
of the horizontal

[[Page 41779]]

stabilizer, which could result in the loss of pitch control and 
consequent reduced controllability of the airplane.

DATES: Effective September 7, 1999.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of September 7, 1999.

ADDRESSES: The service information referenced in this AD may be 
obtained from Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-
2942. 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 FAA, Small 
Airplane Directorate, Wichita Aircraft Certification Office, 1801 
Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas; or at 
the Office of the Federal Register, 800 North Capitol Street, NW., 
suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Jose Flores, Senior Aerospace 
Engineer, Systems and Propulsion Branch, ACE-116W, FAA, Small Airplane 
Directorate, Wichita Aircraft Certification Office, 1801 Airport Road, 
Room 100, Mid-Continent Airport, Wichita, Kansas 67209; telephone (316) 
946-4133; fax (316) 946-4407.
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 Learjet Model 23, 24, 25, 
28, 29, 31, 55, and 60 series airplanes was published in the Federal 
Register on May 17, 1999 (64 FR 26703). That action proposed to require 
a one-time detailed visual inspection of the electrical wire leads of 
the horizontal stabilizer anti-ice system to verify that the numbers on 
the wire leads correctly correspond to the numbers on the connected 
airframe wiring; installation of a wire ID strap on the left-and right-
hand sides of each terminal block; and installation of a warning 
placard.

Comments

    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. No comments were submitted in response 
to the proposal or the FAA's determination of the cost to the public.

Conclusion

    The FAA has determined that air safety and the public interest 
require the adoption of the rule as proposed.

Cost Impact

    There are approximately 1,010 airplanes of the affected design in 
the worldwide fleet. The FAA estimates that 806 airplanes of U.S. 
registry will be affected by this AD, that it will take approximately 1 
work hour per airplane to accomplish the required inspection and 
installations, and that the average labor rate is $60 per work hour. 
Required parts will be provided by the manufacturer at no cost to the 
operators. Based on these figures, the cost impact of the required AD 
on U.S. operators is estimated to be $48,360, or $60 per airplane.
    The cost impact figure discussed above is based on assumptions that 
no operator has yet accomplished any of the proposed 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.

Sec. 39.13  [Amended]

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

99-16-03 Learjet: Amendment 39-11238. Docket 98-NM-372-AD.

    Applicability: Model 23, 24, 25, 28, 29, 31, 55, and 60 series 
airplanes; as listed in Learjet Service Bulletins SB 23/24/25-30-3, 
SB 28/29-30-3, SB 31-30-05, SB 55-30-3, and SB 60-30-4, all dated 
October 27, 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 
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 (b) 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 undetected accretion of ice on the leading edge of 
the horizontal stabilizer, which could result in the loss of pitch 
control and consequent reduced controllability of the airplane, 
accomplish the following:

One-Time Inspection

    (a) Within 100 flight hours after the effective date of this AD: 
Perform a one-time detailed visual inspection of the electrical wire 
leads of the horizontal stabilizer anti-ice system to verify that 
the numbers on the wire leads correctly correspond to the numbers on 
the connected airframe wiring, in accordance with Learjet Service 
Bulletins SB 23/24/25-30-3, (for Model 23, 24, and 25 series 
airplanes), SB 28/29-30-3 (for Model 28 and 29 series airplanes), SB 
31-30-5 (for Model 31 series airplanes), SB 55-30-3 (for Model 55 
series airplanes), or SB 60-30-4 (for Model 60 series airplanes); 
all dated October 27, 1998; as applicable.
    Note 2: For the purposes of this AD, a detailed inspection is 
defined as: ``An intensive visual examination of a specific 
structural area, system, installation or assembly to detect damage, 
failure or irregularity. Available lighting is normally supplemented 
with a direct source of good lighting at intensity deemed 
appropriate by the inspector. Inspection aids such as mirror, 
magnifying lenses, etc. may be used. Surface cleaning and elaborate 
access procedures may be required.''

[[Page 41780]]

Corrective Action

    (1) If no discrepancy is detected during the inspection required 
by paragraph (a) of this AD: Concurrent with the inspection, install 
a wire ID strap on the left-and right-hand sides of each terminal 
block, and install a warning placard on each terminal block, in 
accordance with the applicable service bulletin.
    (2) If any discrepancy is detected during the inspection 
required by paragraph (a) of this AD: Prior to further flight, 
repair the discrepancy in accordance with the procedures specified 
in Chapter 30 of the Learjet Airplane Wiring Manual. Concurrent with 
the repair, install a wire ID strap on the left-and right-hand sides 
of each terminal block, and install a warning placard on each 
terminal block; in accordance with the applicable service bulletin.

Alternative Methods of Compliance

    (b) 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, Wichita Aircraft Certification 
Office (ACO), FAA, Small 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, Wichita ACO.

    Note 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Wichita ACO.

Special Flight Permits

    (c) 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

    (d) Except as provided by paragraph (a)(2) of this AD, the 
actions shall be done in accordance with Learjet Service Bulletin SB 
23/24/25-30-3, dated October 27, 1998; Learjet Service Bulletin SB 
28/29-30-3, dated October 27, 1998; Learjet Service Bulletin SB 31-
30-5, dated October 27, 1998; Learjet Service Bulletin SB 55-30-3, 
dated October 27, 1998; or Learjet Service Bulletin SB 60-30-4, 
dated October 27, 1998, as applicable. 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 Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-
2942. Copies may be inspected at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the 
FAA, Small Airplane Directorate, Wichita Aircraft Certification 
Office, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, 
Kansas; or at the Office of the Federal Register, 800 North Capitol 
Street, NW., suite 700, Washington, DC.
    (e) This amendment becomes effective on September 7, 1999.

    Issued in Renton, Washington, on July 22, 1999.
D. L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 99-19297 Filed 7-30-99; 8:45 am]
BILLING CODE 4910-13-U