83 FR 20740 - Airworthiness Directives; Learjet, Inc. Airplanes

DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration

Federal Register Volume 83, Issue 89 (May 8, 2018)

We propose to adopt a new airworthiness directive (AD) for certain Learjet, Inc. Models 28, 29, 31, 31A, 35, 35A, 36, 36A, 55, 55B, 55C, and 60 airplanes. This proposed AD was prompted by fatigue cracks initiating in the flap support structure due to repetitive flap loads, which has caused flap nose roller support bracket failure. This proposed AD would require replacement of the flap nose roller fitting, nose roller support bracket, and adjacent rib support structure with more robust components. We are proposing this AD to address the unsafe condition on these products.

[Federal Register Volume 83, Number 89 (Tuesday, May 8, 2018)]
[Proposed Rules]
[Pages 20740-20743]
From the Federal Register Online  [www.thefederalregister.org]
[FR Doc No: 2018-09600]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2018-0327; Product Identifier 2018-CE-001-AD]
RIN 2120-AA64


Airworthiness Directives; Learjet, Inc. Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for 
certain Learjet, Inc. Models 28, 29, 31, 31A, 35, 35A, 36, 36A, 55, 
55B, 55C, and 60 airplanes. This proposed AD was prompted by fatigue 
cracks initiating in the flap support structure due to repetitive flap 
loads, which has caused flap nose roller support bracket failure. This 
proposed AD would require replacement of the flap nose roller fitting, 
nose roller support bracket, and adjacent rib support structure with 
more robust components. We are proposing this AD to address the unsafe 
condition on these products.

DATES: We must receive comments on this proposed AD by June 22, 2018.

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 NPRM, contact Learjet, 
Inc., One Learjet Way, Wichita, Kansas 67209; telephone: 316-946-2000; 
email: [email protected]; internet: https://www.bombardier.com. You may view this service information at the FAA, 
Policy and Innovation Division, 901 Locust, Kansas City, Missouri 
64106. For information on the availability of this material at the FAA, 
call (816) 329-4148.

Examining the AD Docket

    You may examine the AD docket on the internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2018-
0327; or in person at Docket Operations between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays. The AD docket contains 
this NPRM, the regulatory evaluation, any comments received, and other 
information. The street address for Docket Operations (phone: 800-647-
5527) is listed above. Comments will be available in the AD docket 
shortly after receipt.

FOR FURTHER INFORMATION CONTACT: Tara Shawn, Aerospace Engineer, 
Wichita ACO Branch, 1801 Airport Road, Room 100, Wichita, Kansas 67209; 
telephone: (316) 946-4141; fax: (316) 946-4107; email: 
[email protected] or [email protected].

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-2018-0327; 
Product Identifier 2018-CE-001-AD'' at the beginning of your comments. 
We specifically invite comments on the overall regulatory, economic, 
environmental, and energy aspects of this NPRM. We will consider all 
comments received by the closing date and may amend this NPRM 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 NPRM.

Discussion

    We received a report of skewed flap and aileron binding due to 
fatigue cracks in the flap support structure caused by repetitive flap 
loads on a Learjet, Inc. Model 31A. As of June 2017, cracks in the flap 
support structure were reported (due to Alert Service Bulletins 
published in March 2017) on Models 31, 31A, 35A, 55, and 60 airplanes. 
Repetitive flap loads occur on all models identified by this proposed 
AD. Failure of the flap nose roller support bracket allows skewed flap 
and aileron binding, which can cause loss of roll control on approach. 
This condition, if not addressed, could result in loss of control.
    Although there have been no reports of cracks on the Models 28, 29, 
35, 36, 36A, 55B, and 55C airplanes, these airplanes do incorporate the 
same design flap support structure.

[[Page 20741]]

Related Service Information Under 1 CFR Part 51

    We reviewed Bombardier Learjet 28/29 Service Bulletin (SB) 28/29-
27-31 Recommended, dated September 11, 2017; Bombardier Learjet 31 SB 
31-27-35 Recommended, dated September 11, 2017; Bombardier Learjet 35/
36 SB 35/36 -27-50 Recommended, dated September 11, 2017; Bombardier 
Learjet 55 SB 55-27-41 Recommended, dated September 11, 2017; and 
Bombardier Learjet 60 SB 60-27-39 Recommended, Revision 1, dated 
January 15, 2018. For the applicable models, the service information 
describes procedures for replacement of the flap nose roller fitting, 
nose roller support bracket, and adjacent rib support structure with 
improved components. The service information also contains instructions 
to ensure correct flap alignment. This service information is 
reasonably available because the interested parties have access to it 
through their normal course of business or by the means identified in 
the ADDRESSES section.

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 This Proposed AD and the Service Information

    The published service information does not list Models 31A, 35A, 
36A, 55B, or 55C as affected models. However, the serial numbers in the 
service information does reflect these models. The serial numbers in 
the service information (except for Models 28/29) does not start with -
001, but the effectivity in this AD starts with -001 for all models. 
The service information for all models also specifies to submit a 
compliance response form to the manufacturer; however, this AD does not 
require that action.

Costs of Compliance

    We estimate that this proposed AD affects 706 airplanes of U.S. 
registry.
    We estimate the following costs to comply with this proposed AD:

                                                 Estimated Costs
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
                Action                         Labor cost          Parts cost *       product        operators
----------------------------------------------------------------------------------------------------------------
Replacement of flap nose roller         188 work-hours x $85 per         $12,213         $28,193     $19,904,258
 fitting, nose roller support bracket,   hour = $15,980.
 and adjacent rib support structure
 with improved components.
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* Parts cost is an average of the composite costs for replacement of all of the kits per airplane. Not all
  airplanes will need all kits, as credit is allowed for some previous installations.


                         Individual Parts Cost *
------------------------------------------------------------------------
                      Kit No. (K/N)                          Part cost
------------------------------------------------------------------------
K/N 2381000-802.........................................            $827
K/N 2381000-804.........................................             822
K/N 2381000-806.........................................             780
K/N 2381000-808.........................................             793
K/N 2381000-809.........................................           1,358
K/N 2381000-810.........................................           1,358
K/N 2381000-811.........................................           1,822
K/N 2381000-817.........................................           1,674
K/N 2381000-818.........................................           1,432
K/N 2381000-819.........................................           1,415
K/N 2381000-820.........................................           1,912
K/N 2381000-821.........................................           1,912
------------------------------------------------------------------------
* Parts required for replacement may vary for different models and
  different airplanes.

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.
    This AD is issued in accordance with authority delegated by the 
Executive Director, Aircraft Certification Service, as authorized by 
FAA Order 8000.51C. In accordance with that order, issuance of ADs is 
normally a function of the Compliance and Airworthiness Division, but 
during this transition period, the Executive Director has delegated the 
authority to issue ADs applicable to small airplanes, gliders, 
balloons, airships, domestic business jet transport airplanes, and 
associated appliances to the Director of the Policy and Innovation 
Division.

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.

[[Page 20742]]

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-2018-0327; Product Identifier 2018-CE-
001-AD.

(a) Comments Due Date

    We must receive comments by June 22, 2018.

(b) Affected ADs

    None.

(c) Applicability

    (1) This AD applies to the following Learjet, Inc. model 
airplanes that are certificated in any category:
[GRAPHIC] [TIFF OMITTED] TP08MY18.005

(d) Subject

    Joint Aircraft System Component (JASC)/Air Transport Association 
(ATA) of America Code 2750, TE Flap Control System.

(e) Unsafe Condition

    This AD was prompted by reports of fatigue cracks initiating in 
the flap support structure due to repetitive flap loads. We are 
issuing this AD to require replacement of the flap nose roller 
fitting, nose roller support bracket, and adjacent rib support 
structure with more robust components. The unsafe condition, if not 
addressed, could cause flap nose roller support bracket failure and 
allow skewed flap and aileron binding, which could result in loss of 
roll control on approach with consequent loss of control.

(f) Compliance

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

(g) Corrective Action

    (1) For Models 28 and 29 airplanes: (i) Within the next 24 
months after the effective date of this AD or within the next 400 
landings after the effective date of this AD, whichever occurs 
first, replace the nose roller fitting, nose roller support bracket, 
and adjacent rib support structure with replacements parts following 
the Accomplishment Instructions in Bombardier Learjet 28/29 Service 
Bulletin (SB) 28/29-27-31 Recommended, dated September 11, 2017.
    (ii) Paragraph 3.B.(1) of the applicable SB for these models 
that have modified flap roller assemblies requires the operator to 
contact Learjet Inc. for repair instructions, and after receiving 
the repair instructions from Learjet, the operator will need to 
request an AMOC as specified in paragraph (j) of this AD in order to 
use the repair.
    (2) For Models 31 and 31A airplanes: Within the next 24 months 
after the effective date of this AD or within the next 400 landings 
after the effective date of this AD, whichever occurs first, replace 
the nose roller fitting, nose roller support bracket and adjacent 
rib support structure with replacements parts following the 
Accomplishment Instructions in Bombardier Learjet 31 SB 31-27-35 
Recommended, dated September 11, 2017.
    (3) For Models 35, 35A, 36, and 36A airplanes: Within the next 
24 months after the effective date of this AD or within the next 400 
landings after the effective date of this AD, whichever occurs 
first, replace the nose roller fitting, nose roller support bracket 
and adjacent rib support structure with replacements parts following 
the Accomplishment Instructions in Bombardier Learjet 35/36 SB 35/
36-27-50 Recommended, dated September 11, 2017.
    (4) For Models 55, 55B, and 55C airplanes: Within the next 24 
months after the effective date of this AD or within the next 400 
landings after the effective date of this AD, whichever occurs 
first, replace the nose roller fitting, nose roller support bracket, 
and adjacent rib support structure with replacements parts following 
the Accomplishment Instructions in Bombardier Learjet 55 SB 55-27-41 
Recommended, dated September 11, 2017.
    (5) For Model 60 airplanes: Within the next 12 months after the 
effective date of this AD or within the next 200 landings after the 
effective date of this AD, whichever occurs first, replace the nose 
roller fitting, nose roller support bracket, and adjacent rib 
support structure with replacement parts following the 
Accomplishment Instructions in Bombardier Learjet 60 SB 60-27-39 
Recommended, Revision 1, dated January 15, 2018.
    (6) For all airplanes: The compliance times in this AD are 
presented in landings. If you do not keep a record of the total 
number of landings, then use a 1-to-1 conversion for hours time-in-
service (TIS) to landings. Example: 20 hours TIS = 20 landings.
    (7) For Models 31, 31A, 35, 35A, 36, 36A, 55, 55B, 55C, and 60 
airplanes: Paragraph 3.B.(2) of the applicable SBs for these models 
that have modified flap roller assemblies requires the operator to 
contact Learjet Inc. for repair instructions, and after receiving 
the repair instructions from Learjet, the operator will need to 
request an alternative method of compliance (AMOC) as specified in 
paragraph (j) of this AD in order to use the repair.

(h) Credit for Previous Actions

    For Model 60 airplanes: This AD allows credit for actions 
required in paragraph (g)(5) of this AD if done before the effective 
date

[[Page 20743]]

of this AD following Bombardier Learjet 60 SB 60-27-39 Recommended, 
Basic Issue, dated September 11, 2017.

(i) No Reporting Requirement

    Although Bombardier Learjet 28/29 SB 28/29-27-31 Recommended, 
dated September 11, 2017; Bombardier Learjet 31 SB 31-27-35 
Recommended, dated September 11, 2017; Bombardier Learjet 35/36 SB 
35/36 -27-50 Recommended, dated September 11, 2017; Bombardier 
Learjet 55 SB 55-27-41 Recommended, dated September 11, 2017; and 
Bombardier Learjet 60 SB 60-27-39 Recommended, Revision 1, dated 
January 15, 2018, all specify to submit a compliance response form 
to the manufacturer per paragraph 3.E., this AD does not require 
that action.

(j) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Wichita ACO branch, 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 certification office, send it to the attention of the 
person identified in paragraph (k)(1) 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 Tara Shawn, 
Aerospace Engineer, Wichita ACO Branch, 1801 Airport Road, Room 100, 
Wichita, Kansas 67209; telephone: (316) 946-4141; fax: (316) 946-
4107; email: [email protected] or [email protected].
    (2) For service information identified in this AD, contact 
Learjet, Inc., One Learjet Way, Wichita, Kansas 67209; telephone: 
316-946-2000; email: [email protected]; internet: https://www.bombardier.com. You may review this referenced service 
information at the FAA, Policy and Innovation Division, 901 Locust, 
Kansas City, Missouri 64106. For information on the availability of 
this material at the FAA, call (816) 329-4148.

    Issued in Kansas City, Missouri, on April 30, 2018.
Melvin J. Johnson,
Deputy Director, Policy & Innovation Division, Aircraft Certification 
Service.
[FR Doc. 2018-09600 Filed 5-7-18; 8:45 am]
 BILLING CODE 4910-13-P