Federal Register / Vol. 86, No. 142 / Wednesday, July 28, 2021 / Proposed Rules 40379 

is being withdrawn, the commenters’ 

requests are no longer necessary. 

Withdrawal of the NPRM constitutes 

only such action and does not preclude 

the FAA from further rulemaking on 

this issue, nor does it commit the FAA 

to any course of action in the future. 

Regulatory Findings 

Since this action only withdraws an 

NPRM, it is neither a proposed AD nor 

a final rule. This action, therefore, is not 

covered under Executive Order 12866 or 

the Regulatory Flexibility Act. 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Incorporation by reference, 

Safety. 

The Withdrawal 

■ Accordingly, the notice of proposed 

rulemaking, which published in the 

Federal Register on July 27, 2018 (83 FR 

35568), is withdrawn. 

Issued on July 21, 2021. 

Gaetano A. Sciortino, 

Deputy Director for Strategic Initiatives, 

Compliance & Airworthiness Division, 

Aircraft Certification Service. 

[FR Doc. 2021–15952 Filed 7–27–21; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2021–0157; Project 

Identifier AD–2020–00483–T] 

RIN 2120–AA64 

Airworthiness Directives; Learjet Inc. 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: The FAA proposes to adopt a 

new airworthiness directive (AD) for 

certain Learjet Inc. (Learjet) Model 45 

airplanes. This proposed AD was 

prompted by reports of corrosion found 

on the upper surface of the lower center 

wing mid spar splice plate. This 

proposed AD would require repetitively 

inspecting the center wing area for 

corrosion and deterioration of protective 

treatments, removing any corrosion, and 

treating any deteriorated areas. The FAA 

is proposing this AD to address the 

unsafe condition on these products. 

DATES: The FAA must receive comments 

on this proposed AD by September 13, 

2021. 

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 

https://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, KS 67209; phone: 

(316) 946–2000; email: ac.ict@

aero.bombardier.com; website: https://

businessaircraft.bombardier.com/en/ 

aircraft/Learjet.html. You may view this 

referenced service information at the 

FAA, Airworthiness Products Section, 

Operational Safety Branch, 901 Locust, 

Kansas City, MO 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 at 

https://www.regulations.gov by 

searching for and locating Docket No. 

FAA–2021–0157; 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, any comments received, and 

other information. The street address for 

Docket Operations is listed above. 

FOR FURTHER INFORMATION CONTACT: Tara 

Shawn, Aviation Safety Engineer, 

Wichita ACO Branch, FAA, 1801 

Airport Road, Wichita, KS 67209; 

phone: (316) 946–4141; fax: (316) 946– 

4107; email: tara.shawn@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

The FAA invites you to send any 

written relevant data, views, or 

arguments about this proposal. Send 

your comments to an address listed 

under ADDRESSES. Include ‘‘Docket No. 

FAA–2021–0157; Project Identifier AD– 

2020–00483–T’’ at the beginning of your 

comments. The most helpful comments 

reference a specific portion of the 

proposal, explain the reason for any 

recommended change, and include 

supporting data. The FAA will consider 

all comments received by the closing 

date and may amend this proposal 

because of those comments. 

Except for Confidential Business 

Information (CBI) as described in the 

following paragraph, and other 

information as described in 14 CFR 

11.35, the FAA will post all comments 

received, without change, to https://

www.regulations.gov, including any 

personal information you provide. The 

agency will also post a report 

summarizing each substantive verbal 

contact received about this NPRM. 

Confidential Business Information 

CBI is commercial or financial 

information that is both customarily and 

actually treated as private by its owner. 

Under the Freedom of Information Act 

(FOIA) (5 U.S.C. 552), CBI is exempt 

from public disclosure. If your 

comments responsive to this NPRM 

contain commercial or financial 

information that is customarily treated 

as private, that you actually treat as 

private, and that is relevant or 

responsive to this NPRM, it is important 

that you clearly designate the submitted 

comments as CBI. Please mark each 

page of your submission containing CBI 

as ‘‘PROPIN.’’ The FAA will treat such 

marked submissions as confidential 

under the FOIA, and they will not be 

placed in the public docket of this 

NPRM. Submissions containing CBI 

should be sent to Tara Shawn, Aviation 

Safety Engineer, Wichita ACO Branch, 

FAA, 1801 Airport Road, Wichita, KS 

67209. Any commentary that the FAA 

receives which is not specifically 

designated as CBI will be placed in the 

public docket for this rulemaking. 

Background 

In December 2018, the FAA received 

a report from Learjet of corrosion found 

in the center wing area of a Model 45 

(Learjet 45) airplane. Exfoliating 

corrosion was found on the upper 

surface of the lower center wing mid 

spar splice plate during unrelated 

maintenance. The corrosion appeared to 

extend half way through the thickness 

of the splice plate. Since the initial 

report, the FAA has received 23 

additional reports of corrosion from 

Learjet. The FAA determined areas of 

the wing center section are not sealed 

against the elements; in addition, the 

fuselage has drain holes that allow 

condensation to drain into the center 

wing. The accumulation and retention 

of moisture in the center wing section 

may lead to corrosion. This condition, if 

not addressed, could result in failure of 

the wing centerline joint and lead to 

partial wing separation with consequent 

loss of control of the airplane. 

FAA’s Determination 

The FAA is issuing this NPRM after 

determining that the unsafe condition 

described previously is likely to exist or 


khammond on DSKJM1Z7X2PROD with PROPOSALS
40380 Federal Register / Vol. 86, No. 142 / Wednesday, July 28, 2021 / Proposed Rules 

develop on other products of the same 

type design. 

Related Service Information Under 1 

CFR Part 51 

The FAA reviewed the following 

service documents proposed for 

compliance with this NPRM: 

• Bombardier Learjet 40 Service 

Bulletin 40–57–06, Revision 1, dated 

October, 26, 2020; 

• Bombardier Learjet 45 Service 

Bulletin 45–57–13, Revision 1, dated 

October, 26, 2020; 

• Bombardier Learjet 70 Service 

Bulletin 70–57–02, Revision 1, dated 

October, 26, 2020; and 

• Bombardier Learjet 75 Service 

Bulletin 75–57–01, Revision 2, dated 

April 19, 2021. 

As applicable to the model 

configuration specified, each service 

bulletin contains procedures for 

inspecting for corrosion and 

deterioration of protective treatments of 

the center wing area from the front spar 

to the rear spar between wing stations 

33.00L to 33.00R, treating deteriorated 

areas, and removing any corrosion. 

Bombardier Learjet 75 Service Bulletin 

75–57–01, Revision 2, dated April 19, 

2021, does not apply to newlymanufactured airplanes, since Learjet 

added this inspection to the 

Airworthiness Limitation Section, 

which will be delivered with new 

airplanes starting at S/N 45–597. 

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. 

Proposed AD Requirements in This 

NPRM 

This proposed AD would require 

accomplishing the actions specified in 

the service information already 

described. This proposed AD would 

also require reporting the inspection 

results to the FAA by email at WichitaCOS@faa.gov. 

Costs of Compliance 

The FAA estimates that this AD, if 

adopted as proposed, would affect 450 

airplanes of U.S. registry. 

The FAA estimates the following 

costs to comply with this proposed AD: 

ESTIMATED COSTS

Action Labor cost Parts cost Cost per 

product 

Cost on U.S. 

operators 

Inspection .......................... 7.50 work-hours × $85 per hour = $637.50 .............. Not applicable .................. $637.50 $286,875 

Reporting to FAA .............. 1 work-hour × $85 per hour = $85 ............................ Not applicable .................. 85 38,250 

The extent of corrosion and 

deterioration of protective treatments 

may vary significantly from airplane to 

airplane. The FAA has no way of 

determining how much damage may be 

found on each airplane, the cost to 

remove the corrosion or treat 

deteriorated areas (or replacing the part, 

if needed), or the number of airplanes 

that may require repair. 

If corrosion is found and removed, the 

FAA estimates that it would take 2 

work-hours per airplane to provide data 

to Learjet. With an average labor rate of 

$85 per work-hour, the FAA estimates a 

cost of $170 per airplane. 

Paperwork Reduction Act 

A federal agency may not conduct or 

sponsor, and a person is not required to 

respond to, nor shall a person be subject 

to a penalty for failure to comply with 

a collection of information subject to the 

requirements of the Paperwork 

Reduction Act unless that collection of 

information displays a current valid 

OMB Control Number. The OMB 

Control Number for this information 

collection is 2120–0056. Public 

reporting for this collection of 

information is estimated to take up to 3 

hours per response, including the time 

for reviewing instructions, searching 

existing data sources, gathering and 

maintaining the data needed, and 

completing and reviewing the collection 

of information. All responses to this 

collection of information are mandatory. 

Send comments regarding this burden 

estimate or any other aspect of this 

collection of information, including 

suggestions for reducing this burden, to: 

Information Collection Clearance 

Officer, Federal Aviation 

Administration, 10101 Hillwood 

Parkway, Fort Worth, TX 76177–1524. 

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. 

The FAA is 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. 

Regulatory Findings 

The FAA 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) Would not affect intrastate 

aviation in Alaska, and 

(3) Would 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 

■ 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. The FAA amends § 39.13 by adding 

the following new airworthiness 

directive: 


khammond on DSKJM1Z7X2PROD with PROPOSALS
Federal Register / Vol. 86, No. 142 / Wednesday, July 28, 2021 / Proposed Rules 40381 

Learjet Inc.: Docket No. FAA–2021–0157; 

Project Identifier AD–2020–00483–T. 

(a) Comments Due Date 

The FAA must receive comments on this 

airworthiness directive (AD) by September 

13, 2021. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to Learjet Inc. Model 45 

(Learjet 40), Model 45 (Learjet 45), Model 45 

(Learjet 70), and Model 45 (Learjet 75) 

airplanes, serial numbers 45–002 through 45– 

596 and 45–2001 through 45–2146, 

certificated in any category. 

(d) Subject 

Joint Aircraft System Component (JASC) 

Code 5714, Wing, Center Box. 

(e) Unsafe Condition 

This AD was prompted by reports of 

corrosion found on the upper surface of the 

lower center wing mid spar splice plate. The 

FAA is issuing this AD to detect and correct 

corrosion or deterioration of protective 

treatments on the center wing area. The 

unsafe condition, if not addressed, could 

result in failure of the wing centerline joint 

and lead to partial wing separation with 

consequent loss of control of the airplane. 

(f) Compliance 

Comply with this AD within the 

compliance times specified, unless already 

done. 

(g) Applicable Service Bulletins 

Use the following service bulletins, as 

applicable to your airplane model 

configuration, to perform the actions required 

by paragraph (h) of this AD: 

(1) Bombardier Learjet 40 Service Bulletin 

40–57–06, Revision 1, dated October 26, 

2020; 

(2) Bombardier Learjet 45 Service Bulletin 

45–57–13, Revision 1, dated October 26, 

2020; 

(3) Bombardier Learjet 70 Service Bulletin 

70–57–02, Revision 1, dated October 26, 

2020; and 

(4) Bombardier Learjet 75 Service Bulletin 

75–57–01, Revision 2, dated April 19, 2021. 

(h) Wing Center Spar Inspection, Related 

Investigative Inspections, and Corrective 

Actions 

At the applicable initial compliance time 

specified in paragraph (h)(1) or (2) of this AD 

and thereafter at intervals not to exceed 8 

years, inspect the center wing area for 

corrosion and deterioration of protective 

treatments and perform all related corrective 

actions by following the Accomplishment 

Instructions, steps 3.A. and 3.B., of the 

applicable service bulletin listed in 

paragraph (g) of this AD. 

(1) For airplanes with 8 or fewer years 

since the date of issuance of the original 

airworthiness certificate or the date of 

issuance of the original export certificate of 

airworthiness, whichever date is earlier: 

Before or upon accumulating 8 years or 

within 12 months after the effective date of 

this AD, whichever occurs later; or 

(2) For airplanes that have accumulated 

more than 8 years since the date of issuance 

of the original airworthiness certificate or the 

date of issuance of the original export 

certificate of airworthiness, whichever date is 

earlier: Within 12 months after the effective 

date of this AD. 

(i) Service Information Exception 

Where Bombardier Learjet 40 Service 

Bulletin 40–57–06, Revision 1, dated October 

26, 2020, Bombardier Learjet 45 Service 

Bulletin 45–57–13, Revision 1, dated October 

26, 2020, Bombardier Learjet 70 Service 

Bulletin 70–57–02, Revision 1, dated October 

26, 2020, and Bombardier Learjet 75 Service 

Bulletin 75–57–01, Revision 2, dated April 

19, 2021, specify contacting Learjet Inc. for 

appropriate action: Before further flight, 

repair using a method approved in 

accordance with the procedures specified in 

paragraph (l) of this AD. 

(j) Reporting Requirement 

Within 30 days after completing the initial 

inspection required by paragraph (h) of this 

AD or within 30 days after the effective date 

of this AD, whichever occurs later, submit a 

report of the findings (both positive and 

negative) of the inspection to: Wichita-COS@

faa.gov; or Ann Johnson, Wichita ACO 

Branch, 1801 Airport Road, Wichita, KS 

67209. This reporting requirement is limited 

to the initial inspection results only. The 

report must include: The name of the owner; 

the address of the owner; the name of the 

organization doing the actions required by 

this AD; the date the inspection was 

completed; the name of the person 

submitting the report; the address, telephone 

number, and email of the person submitting 

the report; the airplane serial number; the 

date of issuance of the original airworthiness 

certificate, or the date of issuance of the 

original export certificate of airworthiness 

(whichever date is earlier); whether 

protective treatments are deteriorated, and if 

so, the location of deteriorated areas; whether 

corrosion was detected, and if so, the 

location of corrosion; and a list of parts 

replaced if the level of corrosion required 

replacement of parts. 

(k) Credit for Previous Actions 

You may take credit for the initial wing 

spar inspection required by the introductory 

text to paragraph (h) of this AD if you 

performed the visual inspection before the 

effective date of this AD using Bombardier 

Learjet 40 Service Bulletin 40–57–06, Basic 

Issue, dated February 25, 2019; Bombardier 

Learjet 45 Service Bulletin 45–57–13, Basic 

Issue, dated February 25, 2019; Bombardier 

Learjet 70 Service Bulletin 70–57–02, Basic 

Issue, dated February 25, 2019; Bombardier 

Learjet 75 Service Bulletin 75–57–01, Basic 

Issue, dated February 25, 2019; or 

Bombardier Learjet 75 Service Bulletin 75– 

57–01, Revision 1, dated October 26, 2020. 

(1) To take credit for the initial inspection, 

you must comply with paragraph (j) of this 

AD within 30 days after the effective date of 

this AD. 

(2) You cannot take credit for the recurring 

inspections, only the initial inspection. 

(l) 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 Related Information. 

(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. 

(3) An AMOC that provides an acceptable 

level of safety may be used for any repair, 

modification, or alteration required by this 

AD if it is approved by a Learjet Inc. 

Designated Engineering Representative, or a 

Unit Member of the Learjet Organization 

Designation Authorization, that has been 

authorized by the Manager, Wichita ACO 

Branch, to make those findings. To be 

approved, the repair, modification, or 

alteration method must meet the certification 

basis of the airplane, and the approval must 

specifically refer to this AD. 

(m) Related Information 

(1) For more information about this AD, 

contact Tara Shawn, Aviation Safety 

Engineer, Wichita ACO Branch, FAA, 1801 

Airport Road, Wichita, KS 67209; phone: 

(316) 946–4141; fax: (316) 946–4107; email: 

tara.shawn@faa.gov. 

(2) For service information identified in 

this AD, contact Learjet Inc., One Learjet 

Way, Wichita, KS 67209; phone: (316) 946– 

2000; email: ac.ict@aero.bombardier.com; 

website: businessaircraft.bombardier.com/ 

en/aircraft/Learjet.html. You may view this 

referenced service information at the FAA, 

Airworthiness Products Section, Operational 

Safety Branch, 901 Locust, Kansas City, MO 

64106. For information on the availability of 

this material at the FAA, call (816) 329–4148. 

Issued on July 21, 2021. 

Gaetano A. Sciortino, 

Deputy Director for Strategic Initiatives, 

Compliance & Airworthiness Division, 

Aircraft Certification Service. 

[FR Doc. 2021–15953 Filed 7–27–21; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2021–0604; Project 

Identifier 2019–CE–007–AD] 

RIN 2120–AA64 

Airworthiness Directives; Pacific 

Aerospace Limited Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 


khammond on DSKJM1Z7X2PROD with PROPOSALS