```

[Federal Register Volume 78, Number 59 (Wednesday, March 27, 2013)]
[Proposed Rules]
[Pages 18531-18533]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2013-07034]

-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2013-0214; Directorate Identifier 2012-NM-152-AD]
RIN 2120-AA64

Airworthiness Directives; Learjet Inc. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Learjet Inc. Model 60 airplanes. This proposed AD was prompted 
by a report of a high-speed rejected takeoff caused by all four main 
landing gear (MLG) tires blowing out during the takeoff roll. This 
proposed AD would require installing new rigid hydraulic tube 
assemblies to the MLG struts, installing a new MLG squat switch 
bracket, modifying the MLG squat switch wire harness, modifying the MLG 
anti-skid wheel transducer electrical wire harnesses, routing and 
securing the anti-skid wheel and squat switch electrical wire harnesses 
to the MLG strut assembly; installing outboard bracket assemblies, 
anti-skid shield, forward electrical cover on the forward stiffener, 
upper and lower inboard bracket assemblies, and clamps that support the 
electrical wire harness; modifying the aft stiffener for the new 
electrical wire harness support; installing the aft electrical cover 
and strap on the aft stiffener; installing a new flat landing light 
lamp if necessary; and, for certain airplanes; installing a new wheel 
speed detect box assembly, nutplates, and brackets and a new thrust 
reverser interface box, and modifying the wiring for the new thrust 
reverser interface box. We are proposing this AD to prevent failure of 
the braking system or adverse operation of the spoiler and thrust 
reverser system due to external damage, particularly from tire failure, 
which could result in loss of control of the airplane.

DATES: We must receive comments on this proposed AD by May 13, 2013.

ADDRESSES: You may send comments, using the procedures found in 14 CFR 
11.43 and 11.45, by any of the following methods:
     Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue SE., Washington, DC 20590.
     Hand Delivery: Deliver to Mail address above between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    For service information identified in this proposed AD, contact 
Learjet, Inc., One Learjet Way, Wichita, KS 67209-2942; telephone 316-
946-2000; fax 316-946-2220; email ac.ict@aero.bombardier.com; Internet 
http://www.bombardier.com. You may review copies of the referenced 
service information at the FAA, Transport Airplane Directorate, 1601 
Lind Avenue SW., Renton, WA. For information on the availability of 
this material at the FAA, call 425-227-1221.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (phone: 800-647-5527) is in the ADDRESSES 
section. Comments will be available in the AD docket shortly after 
receipt.

FOR FURTHER INFORMATION CONTACT: Don Ristow, Aerospace Engineer, 
Mechanical Systems and Propulsion Branch, ACE-116W, FAA, Wichita 
Aircraft Certification Office, 1801 Airport Road, Room 100, Mid-
Continent Airport, Wichita, KS 67209; phone: 316-946-4120; fax: 316-
946-4107; email: donald.ristow@faa.gov.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposal. Send your comments to an address listed 
under the ADDRESSES section. Include ``Docket No. FAA-2013-0214; 
Directorate Identifier 2012-NM-152-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    We received a report of a high-speed rejected takeoff that occurred 
when all four MLG tires blew out during the takeoff roll. The tires 
blew out due to internal heat damage consistent with under-inflation, 
overloading, or a combination of both. Subsequently, damage from tires 
could cause damage to various components, including the MLG squat 
switches, brake hydraulic tubes, wheel speed sensor wiring, and anti-
skid components. In the event of damage to the squat switch wiring, 
thrust reverser operation can be affected adversely. This condition, if 
not corrected, could result in failure of the braking system and 
adverse operation of the spoiler and thrust reverser system, which 
could result in loss of control of the airplane.

Relevant Service Information

    We reviewed Bombardier Service Bulletin SB60-32-33, dated July 23, 
2012. The service bulletin describes procedures for installing new 
rigid hydraulic tube assemblies to the MLG struts; installing a new MLG 
squat switch bracket; modifying the MLG squat switch wire harness; 
modifying the MLG anti-skid wheel transducer electrical wire harnesses; 
and routing and securing the anti-skid wheel and squat switch 
electrical wire harnesses to the MLG strut assembly.
    We reviewed Bombardier Service Bulletin SB60-57-7, dated July 23, 
2012. This service bulletin describes procedures for installing 
outboard bracket assemblies, anti-skid shield, forward electrical cover 
on the forward stiffener, upper and lower inboard bracket assemblies, 
and clamps that support the electrical wire harness; modifying the aft 
stiffener for the new electrical wire harness support; installing the 
aft electrical cover and strap on the aft stiffener; and installing a 
new flat landing light lamp if necessary.
    We reviewed Bombardier Service Bulletin SB60-78-7, Revision 2, 
dated May 1, 2006. For certain airplanes, this service bulletin 
describes procedures for installing a new wheel speed detect box

[[Page 18532]]

assembly, nutplates, and brackets and a new thrust reverser interface 
box, and modifying the wiring for the new thrust reverser interface 
box.

FAA's Determination

    We are proposing this AD because we evaluated all the relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design.

Proposed AD Requirements

    This proposed AD would require accomplishing the actions specified 
in the service information described previously.

Differences Between Proposed Rule and Service Bulletins

    Although Bombardier Service Bulletins SB60-32-33 and SB60-57-7, 
both dated July 23, 2012, recommend accomplishing the modification and 
installation within 600 flight hours or 24 months, whichever occurs 
first, this proposed AD would require compliance within 600 flight 
hours or 12 months, whichever occurs first. In developing an 
appropriate compliance time for this AD, we considered not only the 
manufacturer's recommendation, but the degree of urgency associated 
with addressing the subject unsafe condition, the average utilization 
of the affected fleet, and the time necessary to perform the 
modifications. In light of all of these factors, we find a compliance 
time of within 600 flight hours or 12 months, whichever occurs first, 
for completing the required actions to be warranted, in that it 
represents an appropriate interval of time for affected airplanes to 
continue to operate without compromising safety. This difference has 
been coordinated with the manufacturer.

Related Rulemaking

    On April 1, 2010, we issued AD 2010-11-11, Amendment 39-16316 (75 
FR 32255, June 8, 2010), applicable to Learjet Inc. Model 60 airplanes, 
serial number 60-002 through 60-369 inclusive. That AD currently 
requires revising the Tire-Servicing section of the airplane 
maintenance manual and revising the Tires Limitation section of the 
airplane flight manual to incorporate revised procedures for servicing 
tires and checking for proper tire inflation. That AD was prompted by a 
report of the MLG tires blowing out during a takeoff roll. The actions 
required by that AD are intended to prevent tire failure, which could 
result in failures of the braking and thrust reverser systems; and in a 
critical phase of operation such as takeoff, loss of airplane control 
could result.
    Since issuance of AD 2010-11-11, Amendment 39-16316 (75 FR 32255, 
June 8, 2010), the FAA has determined that the tire pressure check can 
be terminated by accomplishing the actions specified in this proposed 
AD.

Interim Action

    We consider this proposed AD the second of three ADs that are 
related to each other, and collectively address unsafe conditions that 
might result from damage to critical components on the landing gear or 
in the wheel well that affect the braking, spoiler, and thrust reverser 
systems. The manufacturer is currently developing a final modification 
for the thrust reverser. Once the new thrust reverser modification is 
developed, approved, and available, we might consider additional 
rulemaking.

Costs of Compliance

    We estimate that this proposed AD affects 275 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                Action                          Labor cost           Parts cost             Cost per product                Cost on U.S.  operators
--------------------------------------------------------------------------------------------------------------------------------------------------------
Installation of rigid hydraulic tube    Up to 53 work-hours x $85          $7,093  Up to $11,598.....................  Up to $3,189,450.
 assemblies and MLG squat switch         per hour = $4,505.
 bracket; modification of MLG squat
 switch wire harness and MLG anti-skid
 wheel transducer electrical wire
 harnesses; routing and securing anti-
 skid wheel and squat switch
 electrical wire harnesses to MLG
 strut assembly (Bombardier Service
 Bulletin SB60-32-33, dated July 23,
 2012).
Installation of outboard bracket        Up to 25 work-hours x $85          17,960  Up to $20,085.....................  Up to $5,523,375.
 assemblies, anti-skid shield, forward   per hour = $2,125.
 electrical cover, upper and lower
 inboard bracket assemblies, and
 clamps; modification of aft
 stiffener; installation of aft
 electrical cover and strap, and flat
 landing light lamp (Bombardier
 Service Bulletin SB60-57-7, dated
 July 23, 2012).
Installation of wheel speed detect box  Up to 65 work-hours x $85           1,154  $6,679............................  Up to $881,628.
 assembly, nutplates brackets and        per hour = $5,525.
 thrust reverser interface box; and
 modification of wiring for S/Ns 60-
 002 through 60-276 (Bombardier
 Service Bulletin SB60-78-7, Revision
 2, dated May 1, 2006) (132 U.S.
 airplanes).
--------------------------------------------------------------------------------------------------------------------------------------------------------

    According to the manufacturer, some of the costs of this proposed 
AD may be covered under warranty, thereby reducing the cost impact on 
affected individuals. We do not control warranty coverage for affected 
individuals. As a result, we have included all costs in our cost 
estimate.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII: Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701: ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

[[Page 18533]]

Regulatory Findings

    We determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD would not 
have a substantial direct effect 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.
    For the reasons discussed above, I certify this proposed 
regulation:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under the DOT Regulatory Policies 
and Procedures (44 FR 11034, February 26, 1979),
    (3) Will not affect intrastate aviation in Alaska, and
    (4) 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.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

Learjet Inc.: Docket No. FAA-2013-0214; Directorate Identifier 2012-
NM-152-AD.

(a) Comments Due Date

    We must receive comments by May 13, 2013.

(b) Affected ADs

    Certain requirements of this AD affect certain requirements of 
AD 2010-11-11, Amendment 39-16316 (75 FR 32255, June 8, 2010).

(c) Applicability

    This AD applies to Learjet Inc. Model 60 airplanes, certificated 
in any category, serial numbers 60-001 through 60-413 inclusive.

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 32, Landing gear; 57, Wings; 78, Engine 
exhaust.

(e) Unsafe Condition

    This AD was prompted by a report of a high-speed rejected 
takeoff caused by all four main landing gear (MLG) tires blowing out 
during the takeoff roll. We are issuing this AD to prevent failure 
of the braking system or adverse operation of the spoiler and thrust 
reverser system due to external damage, particularly from tire 
failure, which could result in loss of control of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Modification and Installation

    Within 600 flight hours or 12 months after the effective date of 
this AD, whichever occurs first: Do the actions required by 
paragraphs (g)(1), (g)(2), and (g)(3) of this AD, as applicable.
    (1) For all airplanes: Install new rigid hydraulic tube 
assemblies to the MLG struts, install a new MLG squat switch bracket 
and modify the MLG squat switch wire harness, modify the MLG anti-
skid wheel transducer electrical wire harnesses, and route and 
secure the anti-skid wheel and squat switch electrical wire 
harnesses to the MLG strut assembly; in accordance with the 
Accomplishment Instructions of Bombardier Service Bulletin SB60-32-
33, dated July 23, 2012.
    (2) For all airplanes: Install outboard bracket assemblies, 
anti-skid shield, forward electrical cover on the forward stiffener, 
upper and lower inboard bracket assemblies, and clamps that support 
the electrical wire harness; modify the aft stiffener for the new 
electrical wire harness support; install the aft electrical cover 
and strap on the aft stiffener; and install a new flat landing light 
lamp, as applicable; in accordance with the Accomplishment 
Instructions of Bombardier Service Bulletin SB60-57-7, dated July 
23, 2012.
    (3) For airplanes having serial numbers 60-002 through 60-276 
inclusive: Install a new wheel speed detect box assembly, nutplates, 
brackets, and interface box; and modify the wiring for the new 
thrust reverser interface box, in accordance with the Accomplishment 
Instructions of Bombardier Service Bulletin SB60-78-7, Revision 2, 
dated May 1, 2006.

(h) Terminating Action for AD 2010-11-11, Amendment 39-16316 (75 FR 
32255, June 8, 2010)

    After accomplishing the actions required by paragraph (g) of 
this AD, the requirement in paragraph (h) of AD 2010-11-11, 
Amendment 39-16316 (75 FR 32255, June 8, 2010), to check the nose 
and main tire pressures before 96 hours prior to takeoff, is 
terminated. All provisions of paragraphs (g) and (h) of AD 2010-11-
11 that are not specifically referenced by this paragraph remain 
fully applicable and must be complied with.

(i) Credit for Previous Actions

    This paragraph provides credit for the corresponding actions 
specified in paragraph (g)(3) of this AD, if those actions were 
performed before the effective date of this AD using Bombardier 
Service Bulletin SB60-78-7, dated February 21, 2005; or Revision 1, 
dated June 30, 2005; which are not incorporated by reference in this 
AD.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Wichita Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested 
using the procedures found in 14 CFR 39.19. In accordance with 14 
CFR 39.19, send your request to your principal inspector or local 
Flight Standards District Office, as appropriate. If sending 
information directly to the manager of the ACO, send it to the 
attention of the person identified in the Related Information 
section of this AD.
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.

(k) Related Information

    (1) For more information about this AD, contact Don Ristow, 
Aerospace Engineer, Mechanical Systems and Propulsion Branch, ACE-
116W, FAA, Wichita Aircraft Certification Office, 1801 Airport Road, 
Room 100, Mid-Continent Airport, Wichita, KS 67209; phone: 316-946-
4120; fax: 316-946-4107; email: donald.ristow@faa.gov.
    (2) For service information identified in this AD, contact 
Learjet, Inc., One Learjet Way, Wichita, KS 67209-2942; telephone 
316-946-2000; fax 316-946-2220; email ac.ict@aero.bombardier.com; 
Internet http://www.bombardier.com. You may review copies of the 
referenced service information at the FAA, Transport Airplane 
Directorate, 1601 Lind Avenue SW., Renton, WA. For information on 
the availability of this material at the FAA, call 425-227-1221.

    Issued in Renton, Washington, on March 20, 2013.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2013-07034 Filed 3-26-13; 8:45 am]
BILLING CODE 4910-13-P
```