Airworthiness Directives; Learjet Inc. Model 60 Airplanes, 32255-32260 [2010-12676]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 75, Number 109 (Tuesday, June 8, 2010)]
[Rules and Regulations]
[Pages 32255-32260]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-12676]



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DEPARTMENT OF TRANSPORTATION



Federal Aviation Administration



14 CFR Part 39



[Docket No. FAA-2009-0495; Directorate Identifier 2009-NM-049-AD; 

Amendment 39-16316; AD 2010-11-11]

RIN 2120-AA64




Airworthiness Directives; Learjet Inc. Model 60 Airplanes



AGENCY: Federal Aviation Administration (FAA), DOT.



ACTION: Final rule.



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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 

Model 60 airplanes. This AD 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. 

This AD results from a report of the main landing gear tires blowing 

out during a takeoff roll. We are issuing this AD to prevent tire 

failure, which could result in failures of the braking and thrust 

reverser systems. In a critical phase of operation such as takeoff, 

loss of airplane control may result.



DATES: This AD is effective July 13, 2010.

    The Director of the Federal Register approved the incorporation by 

reference of certain publications listed in the AD as of July 13, 2010.



ADDRESSES: For service information identified in this AD, contact 

Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942; telephone 

316-946-2000; fax 316-946-2220; e-mail ac.ict@aero.bombardier.com; 

Internet https://www.bombardier.com.



Examining the AD Docket



    You may examine the AD docket on the Internet at https://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 AD, the regulatory evaluation, 

any comments received, and other information. The address for the 

Docket Office (telephone 800-647-5527) is the Document Management 

Facility, U.S. Department of Transportation, Docket Operations, M-30, 

West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., 

Washington, DC 20590.



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, Kansas 67209; telephone (316) 946-4120; fax 

(316) 946-4107.



SUPPLEMENTARY INFORMATION: 



Discussion



    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 

part 39 to include an airworthiness directive (AD) that would apply to 

certain Model 60 airplanes. That NPRM was published in the Federal 

Register on May 29, 2009 (74 FR 25682). That NPRM proposed to require 

revising the Tire-Servicing section of the airplane maintenance manual 

(AMM) and revising the Tires Limitation section of the airplane flight 

manual (AFM) to incorporate revised procedures for servicing tires and 

checking for proper tire inflation.



Comments



    We gave the public the opportunity to participate in developing 

this AD. We considered the comments received from the 10 commenters.



Support for the NPRM



    The National Transportation and Safety Board (NTSB), and Mike 

Waggoner, a private citizen, support the NPRM. The NTSB states that it 

would prefer that the tires be checked daily for proper pressure, but 

that 96 hours between pressure checks specified in the Tires 

Limitations section of the AFM (specified in paragraph (h) of the NPRM) 

allows for recognition of an under-inflated tire before it reaches a 

point where the tire would need to be changed. Mr. Waggoner agrees that 

a means of bringing attention to the importance of checking tire 

pressures at a minimum of 96 hours before flight is mandatory.



Request To Extend the Comment Period of the Proposed AD



    Aviation Properties requests that we extend the comment period an 

additional 45 days following the release of the NTSB final report on 

the September 19, 2008, accident of a Model 60 airplane. The commenter 

states that all of the relevant information concerning that accident 

has not been determined and made public, and that extending the comment 

period would allow comments to be made with all the data being 

available to everyone.

    We do not agree to extend the comment period and thereby delay the 

AD. While it is true that the final NTSB report is not published, the 

analysis determined with certainty that the tires were subject to 

internal heat damage resulting from under-inflation, overloading, or a 

combination of both. As a result of the tire blow-out, other airplane 

systems were compromised. Based on the design of the Model 60 airplanes 

in particular, we decided to act now to address the unsafe condition. 

If at a later date additional action is deemed appropriate, we might 

consider further rulemaking, which would allow for public comment at 

that time. We have not changed the AD in this regard.



[[Page 32256]]



Requests To Withdraw the NPRM or Certain Requirements



    Aviation Properties states that the proposed AD is unnecessary for 

three reasons: The tires blowing out on takeoff could potentially be 

traced back to improperly serviced tires; the cost of the AD is 

financially overburdening to U.S. operators; and the AD, as proposed, 

could cause another accident because of the possibility that future 

revisions to the AMM might not include the relevant information in the 

temporary revisions. If unaware of the AD, maintenance persons could 

follow a procedure that does not meet the intent of the AD. We infer 

that the commenter requests that we withdraw the NPRM.

    Cloud Nine Aviation states that the AFM requirement of a pre-flight 

pressure measurement is unnecessary, as the Model 60 has been flying 

for 16 years without a problem except one. The commenter further states 

that the cost is overly burdensome, and that pilots know to pay 

particular attention to tire pressures, for which the recent FAA Safety 

Alert for Operators (SAFO 09012, June 12, 2009) has been a good 

reminder. We infer that the commenter believes the SAFO sufficiently 

addresses the unsafe condition stated in the NPRM. We infer that the 

commenter requests that we remove the AFM requirements from the NPRM.

    We do not agree to withdraw the NPRM or to remove the proposed AFM 

requirements. A review of the Model 60 airplane shows a vulnerability 

to system damage due to a blown tire. Rarely is an accident caused by a 

single event, but rather by a series of events. The AD addresses tire 

inflation pressure, which would mitigate one event of a possible chain 

of events that can lead to an accident. The AD, which requires that the 

temporary revisions be inserted into the AMM and the temporary changes 

be inserted into the AFM, is the appropriate vehicle to address this 

issue and is necessary to prevent the unsafe condition. The AD requires 

that the relevant information from the temporary revisions (TRs) be in 

the general revisions before the TRs can be removed. We have not 

changed the AD in this regard.

    We address the issue of costs in our response to ``Requests to 

Revise the Costs of Compliance'' later in this section of the AD.



Request for Information on Global Efforts for Tire Safety



    Electrolux Home Products (Electrolux) notes that Bombardier 

Advisory Wire 32-046 ``is one element of a strategic effort to promote 

safety across the entire aviation industry with respect to proper tire 

inflation,'' and asks if the FAA will follow suit.

    From this request we infer that the commenter is asking if the FAA 

plans to publish further tire safety information applying to the entire 

aviation industry. No additional publications are planned at this time. 

FAA Advisory Circular (AC) 20-97B, dated April 18, 2005, provides 

guidance on the installation, inflation, maintenance, and removal of 

tires. In addition, that AC provides guidance on those operational 

practices necessary to maintain safe airplane operations. More 

recently, the FAA Flight Standards Service has twice published a safety 

alert for operators (SAFO), titled ``Dangers of Improperly Inflated 

Tires.'' No change to this AD is necessary.



Request for Training



    Aviation Properties and William Detig, a private citizen, suggest 

that training is needed. Aviation Properties asks if there is a plan to 

develop educational material and awareness in lieu of mandating tire 

pressure checks for one specific airplane model, while Mr. Detig 

proposes training pilots to monitor tire pressures with calibrated tire 

gauges, and to comply with required preflight checks to determine that 

tires are in airworthy condition.

    We know of no plans for training on this issue at this time. For 

specific information on tires and tire pressure, FAA Advisory Circular 

(AC) 20-97B, dated April 18, 2005, titled ``Aircraft Tire Maintenance 

and Operational Practices,'' can be found at https://www.rgl.faa.gov. 

The AC provides recommended tire care and maintenance practices needed 

to assure the safety of support personnel and the continued 

airworthiness of airplanes. Specifically, the AC provides guidance on 

the installation, inflation, maintenance, and removal of airplane 

tires. In addition, the AC provides guidance on those operational 

practices necessary to maintain safe airplane operations. We have not 

changed this AD in this regard.



Requests To Include Other Airplane Models in the Applicability



    Electrolux, Chantilly Air, Goodyear Tire & Rubber Company 

(Goodyear), Aviation Properties, the NTSB, and private citizens Mike 

Waggoner and William Detig request that we expand the applicability of 

the NPRM to include other airplane models. In summary, the commenters 

state that checking tire pressure should not be limited to just the 

Model 60 airplanes, that other accidents and incidents have involved 

the Model 35 and Model 55 airplanes, and that this issue is relevant to 

all business jets and other large airplanes and to those with high 

takeoff and landing speeds.

    Electrolux states that tire pressure is a maintenance issue, which 

is relevant to all business jets and other large airplanes, and that 

Bombardier has issued Advisory Wires 32-046, dated December 10, 2008, 

and 32-047, dated March 11, 2009, applying to all models and specifying 

that tire pressures must be checked prior to the first flight of the 

day.

    Chantilly Air states that tire pressure is not just a Model 60 

issue, because the incident described in the NPRM is one of many in 

which malfunctioning airplane tires may have been a safety issue.

    Goodyear states that its recommendations for checking tire pressure 

should be incorporated into maintenance programs for the Model 60 

airplanes and all airplanes.

    Aviation Properties states that improper servicing of tires is a 

danger to any airplanes certified in any category made by any 

manufacturer, that the Model 60 airplanes should not be discriminated 

against, and that any AD written with reference to tire servicing 

procedures should be written to include all certified airplanes.

    The NTSB states that the risk of unsafe tire pressure is not 

limited to the Model 60 airplanes, and the NPRM should be expanded to 

include at least Model 55 airplanes (since the Model 60 airplane design 

is based on the Model 55 airplane design) and any airplanes that have 

high rates of multiple tire failure or that are equipped with tires 

operating near their margin of safety.

    Mr. Waggoner states that several accidents and incidents have 

occurred due to improperly serviced tires, that issuing an AD against 

the Model 60 airplanes will not resolve the problem that all airplanes 

with high takeoff and landing speeds experience, and that the industry 

should do more than issue an AD against any one airplane model.

    Mr. Detig states that all airplanes would be subject to the 

identified unsafe condition if the pilots try to take off with tires 

that are under-serviced.

    We partially agree with the commenters. We agree that the 

importance of ensuring proper tire inflation pressure cannot be over-

emphasized, especially on high-performance airplanes. To this end, both 

Learjet and Goodyear provide tire-care and maintenance instructions. We 

also published Advisory Circular 20-97B (Aircraft Tire Maintenance and



[[Page 32257]]



Operational Practices, April 18, 2005) that is applicable to all 

airplane tires.

    However, we do not agree to expand the AD applicability to include 

other airplanes. This AD applies to the Model 60 airplanes because of 

the disproportionate number of tire failure events per number of 

airplanes built, compared to other models. From the data gathered from 

service difficulty reports, the Model 60 airplanes have more than twice 

the number of tire failure events as the Model 30 series and a third 

greater rate than the Model 55 series. While the Models 55 and 60 

airplanes are similar in design, the Model 60 airplane has a higher 

gross weight and tire pressure than the Model 55 airplane. In addition, 

a review of the hydraulic, brake, and thrust reverser systems of the 

Model 60 airplanes has revealed their vulnerability to damage due to a 

burst tire. For these reasons, we have determined that an unsafe 

condition exists and is more likely to occur in the Model 60 airplanes 

than other models of business jets. If we learn that other airplanes 

blow out tires to the same extent as the Model 60 airplanes and have 

similar system vulnerability, we might consider additional rulemaking. 

We have not changed the AD in this regard.



Requests To Reduce the Pressure Check Interval



    Mike Waggoner and Goodyear request that we remove the 96-hour 

requirement to check tire pressure and replace it with a check prior to 

the first flight of the day. To summarize, the commenters state that 

the Learjet 60 AMM, the Goodyear Aircraft Tire Care And Maintenance 

Manual, and FAA Advisory Circular 20-97B all recommend that tire 

pressure checks be conducted daily.

    Mr. Waggoner recommends performing a tire condition and pressure 

check on all airplanes with high takeoff and landing speeds a minimum 

of 24 hours prior to takeoff, which could be done with available 

technology without the need to hook up tire pressure gauges.

    Goodyear states that its Aircraft Tire Care and Maintenance Manual, 

and FAA Advisory Circular 20-97B, recommend that tire pressure checks 

be conducted daily for the Model 60 airplanes and all airplanes. 

Goodyear sees no reason to depart from its recommendation for checking 

pressure daily or prior to the first flight of the day when tires are 

cool (at ambient temperature).

    We do not agree to require daily pressure checks. While checking 

tire pressure daily is encouraged, regulations do not require it unless 

specifically made a part of an inspection program specified by sections 

91.409(e) and 91.409(f) of the Federal Aviation Regulations (14 CFR 

91.409(e) and 91.409(f)), or an airworthiness limitation or AD action. 

According to this AD, the tire pressure check would be applied 

uniformly to all affected airplanes. To minimize the impact on 

operators of the affected airplanes, we considered the daily average 

tire pressure leakage rate and determined that with a properly serviced 

tire, a period of up to four days (96 hours) could be allowed and still 

be within a safe pressure range. For this reason, we can still mitigate 

an unsafe condition and provide some flexibility to the airplane 

operators. We have not changed the AD in this regard.



Requests for an Exemption Allowing Certain Pilots to Check Tire 

Pressure



    Learjet, Chantilly Air, Goodyear, and Tim Rounds, a private 

citizen, request that we issue an exemption to section 43.3(g) of the 

Federal Aviation Regulations (14 CFR 43.3(g)) that would allow pilots 

operating under part 135 of the Federal Aviation Regulations (14 CFR 

part 135) to perform tire pressure checks. To summarize, the commenters 

state that, without the exemption, only a certificated mechanic could 

check tire pressure under 14 CFR part 135 operating rules. Conversely, 

under part 91 of the Federal Aviation Regulations (14 CFR part 91), a 

pilot is allowed to perform the same tire pressure check.

    Learjet states that not allowing properly trained pilots of 14 CFR 

part 135 airplanes to check tire pressure might overshadow the intended 

consequence of the NPRM, which is to prevent tire failures, and that 

the proposed AD can and should authorize all properly trained pilots to 

conduct pressure checks.

    Chantilly Air requests that we address the issue of pilots under 14 

CFR part 135 not being able to do the pressure checks, which is no more 

or less difficult than checking oil on preflight. Similarly, Goodyear 

states that, with an exemption in place for 14 CFR part 135 operators, 

tire pressure can be checked by the pilot.

    Mr. Rounds requests that an exemption be incorporated into the AD 

for 14 CFR parts 121, 129, and 135 pilots, because some local 

Certificate-Holding District Offices are reluctant to issue such an 

exemption even after training requirements suggested by Bombardier 

Advisory Wire 32-047 have been submitted and aircrews have been 

trained.

    We do not agree to issue an exemption to an operating rule with 

this AD. The AD is intended to globally address an unsafe condition by 

specifying special maintenance practices, regardless of the operating 

rules used. The owner/operator of the airplane determines its intended 

use and, in turn, what set of operating and maintenance procedures 

apply. It is not our intent to distinguish or specify in this AD who 

can perform a tire pressure check, nor to amend or change an existing 

rule in 14 CFR part 43. For this reason, we will treat a request or 

petition for exemption as a separate action to this AD. We have not 

changed the AD in this regard.



Requests To Revise the Costs of Compliance



    Cloud Nine Aviation, Aviation Properties, and Chantilly Air request 

that we revise the Costs of Compliance section of the NPRM to include 

the cost of recurring actions and materials. To summarize, the 

commenters state that the cost estimate covers only one event per 

airplane and not the recurring action.

    Cloud Nine Aviation states that the cost of additional preflight 

tire servicing will be substantial, putting the Model 60 airplanes at 

an economic disadvantage as a charter airplane. The commenter also 

states that costs can accumulate and the actions might be needed more 

than every 96 work hours as specified in the TRs described in the NPRM, 

and that the costs of compliance estimate in the NPRM ignores these 

costs to the operator.

    Aviation Properties states that the costs listed in the NPRM cover 

only one event per airplane and do not consider the recurring action 

that will be required, and that each event will be required at least 

every 10 days and as much as every 4 days. The commenter gives an 

example of the annual costs at those intervals.

    Chantilly Air states that the burden of more costs is being put on 

the operator, especially if hangar time is needed in very cold weather, 

and states that they have been charged $95 to $140 per hour to comply 

with the TRs as proposed in the NPRM.

    We do not agree to revise the Costs of Compliance section of this 

AD as requested. Based on the best data available, the manufacturer 

provided an estimate of one work-hour necessary to do the required 

actions--in this case, to revise the AFM and AMM.

    The number of work-hours represents the time necessary to perform 

only the actions actually required by this AD. We recognize that 

operators might incur incidental costs in addition to the direct costs. 

The cost analysis in AD



[[Page 32258]]



rulemaking actions, however, typically does not include incidental 

costs such as the time required to gain access and close up, time 

necessary for planning, or time necessitated by other administrative 

actions. Those incidental costs, which might vary significantly among 

operators, are almost impossible to calculate.

    Because ADs require explicit actions to address specific unsafe 

conditions, they appear to impose costs that would not otherwise be 

borne by operators. However, because operators are obliged to maintain 

and operate their airplanes in an airworthy condition, this appearance 

is deceptive. Attributing those costs solely to the issuance of this AD 

is unrealistic because, in the interest of maintaining and operating 

safe airplanes, prudent operators would accomplish the required actions 

even if they were not required to do so by the AD. In any case, we have 

determined that the safety benefits of the AD still outweigh the direct 

and incidental costs. We have not changed the AD in this regard.



Request for Definition of ``Cold''



    Cloud Nine Aviation states that ``cold tire in service pressure'' 

is referenced in Table 301 of Learjet TR 12-16, dated March 18, 2009, 

to the Learjet 60 Maintenance Manual (specified in paragraph (g) of 

this AD), and requests that we define ``cold'' as it relates to tire 

pressure.

    We agree to define the term. The TR refers to ``cold tire operating 

pressure range.'' Rather than defining cold as a specific temperature, 

it is the ambient temperature when the tire has been at rest for a 

period of time, generally at least 2 hours since use. We have not 

changed the AD in this regard.



Request for Information About Temperature Changes



    Chantilly Air requests information concerning a specific scenario, 

as follows. Within the content of Learjet TR 12-16, dated March 18, 

2009, to the Learjet 60 Maintenance Manual, in very cold climates, the 

airplane tire pressure has been increased to adjust for a temperature 

drop, which will occur once the airplane is moved outside the hangar 

and has not had a chance to cold soak prior to a quick departure.

    We agree to provide the following information. In the scenario 

presented by the commenter, the airplane should be serviced to readjust 

the tire pressure to within the normal operating range if it is outside 

the allowable pressure range. Learjet TR 12-16, dated March 18, 2009, 

specifies to adjust the tire pressure to account for temperature 

changes if the airplane will be parked for more than one hour. If 

departure is sooner, the tire pressure should be readjusted 

accordingly. We have not changed the AD in this regard.



Request for Clarification of Logbook Entry Requirements



    Chantilly Air requests that we clarify why, within the content of 

Learjet TR 12-16, dated March 18, 2009, to the Learjet 60 Maintenance 

Manual, an airplane logbook entry is not required for the tire pressure 

check.

    We agree to clarify why a logbook entry is not required. A 

maintenance record could be made in the traditional airplane logbook. 

However, as a practical matter, we do not advocate carrying this 

logbook aboard the airplane. Alternatively, according to FAA Advisory 

Circular 43-9C, dated June 8, 1998, titled ``Maintenance Records,'' the 

maintenance records may be kept in any format that provides continuity, 

includes required contents, lends itself to the addition of new 

entries, provides for signature entry, and is intelligible. Airplane 

logbooks are one form of recording maintenance. For the purposes of 

this AD, the example of a tire pressure check record given in Learjet 

TR 12-16, dated March 18, 2009, is one method that meets this 

requirement. We have not changed the AD in this regard.



Request for Definition



    Cloud Nine Aviation requests that we define, within the content of 

Learjet TR 12-16, dated March 18, 2009, to the Learjet 60 Maintenance 

Manual, what is meant by keeping the dual main gear tire pressures ``as 

close as possible.''

    We agree to define the term. The specified normal cold tire 

operating pressure range (10 pounds per square inch gauge difference) 

is sufficient. Ideally, the closer the pressures are, the better to 

minimize unequal tire loading between adjacent tires. We have not 

changed the AD in this regard.



Request for Clarification



    Aviation Properties requests that we clarify the difference between 

``will'' and ``should'' for checking tire pressure on airplanes parked 

for extended periods (10 or more consecutive days) within the content 

of Learjet TR 12-16, dated March 18, 2009, to the Learjet 60 

Maintenance Manual, and Temporary Flight Manual Change 2009-03, dated 

March 9, 2009, to the Learjet 60 and Learjet 60XR AFMs.

    We agree to clarify the terms following a discussion with Learjet 

Inc. In the AFM, the term ``will'' does not mean that a tire pressure 

check is required every 10 days. The appropriate reference for 

servicing the tires is the AMM. Chapter 12 of the AMM stipulates the 

minimum acceptable tire pressure ranges and associated actions (Table 

301) and recommends that the tire pressures ``should'' be checked every 

10 days while the airplane is parked. It is up to the individual owner/

operator to determine if every 10 days is feasible. However, if the 

tires have been rolled or taxied below the minimums specified in the 

AMM, they may not be used and are scrap. We have not changed the AD in 

this regard.



Request for Clarification of AMM Requirement



    Aviation Properties requests that we clarify what is required by 

the AMM versus section 43.9 of the Federal Aviation Regulations (14 CFR 

43.9). The commenter states that Learjet TR 12-16, dated March 18, 

2009, to the Learjet 60 Maintenance Manual, required as proposed in the 

NPRM, specifies both the date and time of each pressure check, while 14 

CFR 43.9 requires only the date.

    We agree to clarify the requirement. The step-by-step instructions 

remain in the appropriate chapter of the AMM. As the commenter 

mentions, 14 CFR 43.9 does not require recording time of completion or 

documentation of tire pressure values. However, the critical aspect of 

this AD is time. We specified 96 hours between tire pressure checks to 

be more precise, as opposed to calendar days which could potentially 

lead to a longer interval between checks. Therefore, it is an 

additional requirement above the minimum specified in 14 CFR 43.9.

    We placed the tire pressure check requirement in the AFM to 

emphasize to the flightcrew the critical nature of tire pressure for 

safely operating the airplane. We decided that the pilot, as the person 

ultimately responsible for the outcome of the flight, should be made 

directly aware of this requirement and be able to take steps to ensure 

that it is satisfied. We have not changed the AD in this regard.



Request for Information About AMM Reference



    Aviation Properties states that within the content of Learjet TR 

12-16, dated March 18, 2009, to the Learjet 60 Maintenance Manual, the 

statement ``Do not decrease pressure of a hot tire'' could not be found 

in the previous revision of Section 12-10-05, Section 1, of the Learjet 

60 Maintenance Manual. The commenter speculates that since the 

statement was not in the previous



[[Page 32259]]



revision, the tires on the incident airplane may have been under-

serviced.

    We infer that the commenter requests that we clarify the manual 

reference. The quoted statement is found in Section 12-10-05, Section 

1, Paragraph 15(f), of the previous revision of the Learjet 60 

Maintenance Manual dated June 27, 2005. We have not changed the AD in 

this regard.



Explanation of Change Made to This AD



    We have revised this AD to identify the legal name of the 

manufacturer as published in the most recent type certificate data 

sheet for the affected airplane models.



Conclusion



    We reviewed the relevant data, considered the comments received, 

and determined that air safety and the public interest require adopting 

the AD with the change described previously. We also determined that 

this change will not increase the economic burden on any operator or 

increase the scope of the AD.



Explanation of Change to Costs of Compliance



    Since issuance of the NPRM, we have increased the labor rate used 

in the Costs of Compliance from $80 per work-hour to $85 per work-hour. 

The Costs of Compliance information, below, reflects this increase in 

the specified hourly labor rate.



Costs of Compliance



    We estimate that this AD affects 240 airplanes of U.S. registry. We 

also estimate that it takes about 1 work-hour per product to comply 

with this AD. The average labor rate is $85 per work-hour. Based on 

these figures, we estimate the cost of this AD to the U.S. operators to 

be $20,400, or $85 per product.



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.



Regulatory Findings



    This AD will not have federalism implications under Executive Order 

13132. This AD will 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 that this AD:

    (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.

    You can find our regulatory evaluation and the estimated costs of 

compliance in the AD Docket.



List of Subjects in 14 CFR Part 39



    Air transportation, Aircraft, Aviation safety, Incorporation by 

reference, Safety.



Adoption of the Amendment



0

Accordingly, under the authority delegated to me by the Administrator, 

the FAA amends 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 AD:



2010-11-11 Learjet Inc.: Amendment 39-16316. Docket No. FAA-2009-

0495; Directorate Identifier 2009-NM-049-AD.



Effective Date



    (a) This airworthiness directive (AD) is effective July 13, 

2010.



Affected ADs



    (b) None.



Applicability



    (c) This AD applies to Learjet Inc. Model 60 airplanes, 

certificated in any category, serial numbers 60-002 through 60-369 

inclusive.



Subject



    (d) Air Transport Association (ATA) of America Code 32: Landing 

gear.



Unsafe Condition



    (e) This AD results from a report of the main landing gear tires 

blowing out during a takeoff roll. The Federal Aviation 

Administration is issuing this AD to prevent tire failure, which 

could result in failures of the braking and thrust reverser systems. 

In a critical phase of operation such as takeoff, loss of airplane 

control may result.



Compliance



    (f) You are responsible for having the actions required by this 

AD performed within the compliance times specified, unless the 

actions have already been done.



Revise the Maintenance Manual (MM)



    (g) Within 14 days after the effective date of this AD, revise 

the Tire--Servicing Section of the Learjet 60 MM to include the 

information in Learjet 60 Temporary Revision (TR) 12-16, dated March 

18, 2009.



    Note 1: The actions required by paragraph (g) of this AD may be 

done by inserting a copy of Learjet 60 TR 12-16, dated March 18, 

2009, into the Learjet 60 MM. When the TR has been included in 

general revisions of the Learjet 60 MM, the general revisions may be 

inserted in the MM, provided the relevant information in the general 

revision is identical to that in the TR.



Revise the Airplane Flight Manual (AFM)



    (h) Within 14 days after the effective date of this AD, revise 

the Tires Limitations Section of the Learjet 60 AFM or Learjet 60XR 

AFM, as applicable, to include the information in the Learjet 60 

Temporary Flight Manual Change (TFMC) 2009-03, dated March 9, 2009. 

Thereafter, operate the airplane according to the limitations and 

procedures in the TFMC.



    Note 2: The actions required by paragraph (h) of this AD may be 

done by inserting a copy of Learjet 60 TFMC 2009-03, dated March 9, 

2009, into the Learjet 60 AFM or Learjet 60XR AFM, as applicable. 

When Learjet 60 TFMC 2009-03 has been included in general revisions 

of the applicable AFM, the general revisions may be inserted in the 

applicable AFM, provided the relevant information in the general 

revision is identical to that in the TFMC.



Alternative Methods of Compliance (AMOCs)



    (i)(1) The Manager, Wichita Aircraft Certification Office, FAA, 

has the authority to approve AMOCs for this AD, if requested using 

the procedures found in 14 CFR 39.19. Send information to Attn: Don 

Ristow, Aerospace Engineer, Mechanical Systems and Propulsion 

Branch, ACE-116W, Wichita Aircraft Certification Office, FAA, 1801 

Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 

67209; telephone (316) 946-4120; fax (316) 946-4107.

    (2) To request a different method of compliance or a different 

compliance time for this AD, follow the procedures in 14 CFR 39.19. 

Before using any approved AMOC on any airplane to which the AMOC 

applies,



[[Page 32260]]



notify your principal maintenance inspector (PMI) or principal 

avionics inspector (PAI), as appropriate, or lacking a principal 

inspector, your local Flight Standards District Office. The AMOC 

approval letter must specifically reference this AD.



Material Incorporated by Reference



    (j) You must use Learjet 60 Temporary Revision 12-16, dated 

March 18, 2009, to the Learjet 60 Maintenance Manual; and Learjet 60 

Temporary Flight Manual Change 2009-03, dated March 9, 2009, to the 

Learjet 60 or Learjet 60XR Airplane Flight Manual; as applicable; to 

do the actions required by this AD, unless the AD specifies 

otherwise. (The issue date of Learjet 60 Temporary Flight Manual 

Change 2009-03 is specified only on the first page of the document.)

    (1) The Director of the Federal Register approved the 

incorporation by reference of this service information under 5 

U.S.C. 552(a) and 1 CFR part 51.

    (2) For service information identified in this AD, contact 

Learjet, Inc., One Learjet Way, Wichita, Kansas 67209-2942; 

telephone 316-946-2000; fax 316-946-2220; e-mail 

ac.ict@aero.bombardier.com; Internet https://www.bombardier.com.

    (3) You may review copies of the service information at the FAA, 

Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 

Washington. For information on the availability of this material at 

the FAA, call 425-227-1221 or 425-227-1152.

    (4) You may also review copies of the service information that 

is incorporated by reference at the National Archives and Records 

Administration (NARA). For information on the availability of this 

material at NARA, call 202-741-6030, or go to: https://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.



    Issued in Renton, Washington, on April 1, 2010.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification 

Service.

[FR Doc. 2010-12676 Filed 6-7-10; 8:45 am]

BILLING CODE 4910-13-P