### 32255 Federal Register / Vol. 75, No. 109 / Tuesday, June 8, 2010 / Rules and Regulations

TABLE 

### 1—M ATERIAL 

### I NCORPORATED BY 

### R EFERENCE

Thielert Service Bulletin No. Page Revision Date

TM TAE 125–1007 P1 ....................................................................................................... ALL ... ........... 2 April 29, 2009. Total Pages: 4
TM TAE 125–1009 P1 ....................................................................................................... ALL ... ........... 3 October 14, 2009. Total Pages: 26
TM TAE 125–0018 ............................................................................................................. ALL .............. 1 November 12, 2008. Total Pages: 2 TM TAE 125–0020, including Annexes A and B ............................................................... ALL .............. 1 Nov ember 25, 2009. Total Pages: TM TAE 125–0020, 42; Annex A, 3; Annex B, 4

Issued in Burlington, Massachusetts, on May 19, 2010. Tracy Murphy, Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.

[FR Doc. 2010–12540 Filed 6–7–10; 8:45 am]

**BILLING CODE 4910–13–P**

**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.

**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 http://www.bombardier.com.

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 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 underinflated 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.


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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 http:// 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 tireinflation pressure cannot be overemphasized, especially on highperformance 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


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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 135pilots, because some local CertificateHolding 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


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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


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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 theCosts of Compliance from $80 per workhour 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 workhour. 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

■ Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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 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,


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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 http://
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: http://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**

**DEPARTMENT OF TRANSPORTATION**

**Federal Aviation Administration**

**14 CFR Part 39**

**[Docket No. FAA–2009–0982; Directorate Identifier 2009–NE–19–AD; Amendment 39–**  **16323; AD 2010–12–02]**

**RIN 2120–AA64**

**Airworthiness Directives; Turbomeca**
**S.A. MAKILA 1A and 1A1 Turboshaft Engines** 

**AGENCY :**  Federal Aviation Administration (FAA), DOT.

**ACTION :**  Final rule.

**SUMMARY :**  We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct
an unsafe condition on an aviation product. The MCAI describes the unsafe
condition as:

The installation of TU250 comparator/ selector (CS) boards, however, has resulted in a few occurrences of erratic engine behaviour, in the form of unexpected N1
variations and/or illumination of the ‘‘ GOV’’ warning light. The conclusions from an investigation by Turbome  ́ ca are that these malfunctions are due to a lapse of quality control in the varnishing process applied to the boards, and that only boards in a specific serial number range, as defined under

‘‘Applicability ’’ and referred to below as the

‘‘ suspect batch ’’ , are affected.
We are issuing this AD to prevent loss of automatic engine control during flightdue to an uncommanded engine rollback, which could result in the inability to continue safe flight.

**DATES :**  This AD becomes effective July 13, 2010. The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of July 13, 2010.

**ADDRESSES :**  The Docket Operations office is located at Docket Management Facility, U.S. Department of Transportation, 1200 New Jersey Avenue, SE., West Building Ground Floor, Room W12–140, Washington, DC

20590–0001.

**FOR FURTHER INFORMATION CONTACT :**  Kevin Dickert, Aerospace Engineer, Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA

01803; e-mail: kevin.dickert@faa.gov; telephone (781) 238–7117, fax (781)

238–7199.

**SUPPLEMENTARY INFORMATION :** 

Discussion

We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to include an AD that would apply to the specified products. That NPRM was published in the Federal Register on March 31, 2010 (75 FR 16022). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states that:

The installation of TU250 CS boards, however, has resulted in a few occurrences of erratic engine behaviour, in the form of unexpected N1 variations and/or
illumination of the ‘‘ GOV’’ warning light. The conclusions from an investigation by
Turbomeca are that these malfunctions are due to a lapse of quality control in the varnishing process applied to the boards, and that only boards in a specific serial number range, as defined under ‘‘ Applicability ’’ and referred to below as the ‘‘ suspect batch ’’ , are affected.

Comments

We gave the public the opportunity to participate in developing this AD. We
received no comments on the NPRM or
on the determination of the cost to the public.

Conclusion

We reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed.

Costs of Compliance

Based on the service information, we
estimate that this AD will affect about 10 products of U.S. registry. We also
estimate that it will take about 1 workhour per product to comply with this AD. The average labor rate is $85 per work-hour. Required parts will cost about $3,500 per product. Based on these figures, we estimate the cost of the AD on U.S. operators to be $35,850.

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

We determined that 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 this AD:

1. Is not a ‘‘ significant regulatory

action ’’ under Executive Order 12866;