### 35613 Federal Register / Vol. 75, No. 120 / Wednesday, June 23, 2010 / Rules and Regulations

(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, 3855 Lakewood Boulevard, MC D800–0019, Long Beach, California 90846– 0001; telephone 206–544–5000, extension 2; fax 206–766–5683; e-mail dse.boecom@boeing.com; Internet https:// www.myboeingfleet.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.

(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 June 10,
2010. Jeffrey E. Duven, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 2010–14982 Filed 6–22–10; 8:45 am]

**BILLING CODE 4910–13–P**

**DEPARTMENT OF TRANSPORTATION**

**Federal Aviation Administration**

**14 CFR Part 39**

**[Docket No. FAA–2009–0995; Directorate Identifier 2009–NM–123–AD; Amendment**  **39–16336; AD 2010–13–05]**

**RIN 2120–AA64**

**Airworthiness Directives; Bombardier, Inc. Model CL–600–2C10 (Regional Jet**  **Series 700 & 701) Airplanes, Model CL– 600–2D15 (Regional Jet Series 705)**  **Airplanes, and Model CL–600–2D24 (Regional Jet Series 900) Airplanes** 

**AGENCY :**  Federal Aviation Administration (FAA), Department of Transportation (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) originated 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:

Investigation into a landing gear retraction problem on a production test flight revealed that, during aircraft pressurization and depressurization cycles, the pressure floor in the main landing gear bay deflects to a small extent. This causes relative misalignment between the [alternate-extension system] AES bypass valve, the downlock assist valve and the summing lever which, in turn, can result in damage to and potential failure of the respective clevis attached to one or both of the valves. Such a clevis failure could remain dormant and, in the subsequent event that use of the AES was required, full landing gear extension may not be achievable.
* * * * *

We are issuing this AD to require actions to correct the unsafe condition on these products.

**DATES :**  This AD becomes effective June 23, 2010.

The Director of the Federal Register approved the incorporation by reference of certain publications listed in this AD as of July 28, 2010.

**ADDRESSES :**  You may examine the AD docket on the Internet at http:// www.regulations.gov or in person at the U.S. Department of Transportation, Docket Operations, M–30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue SE., Washington, DC.

**FOR FURTHER INFORMATION CONTACT :**  Cesar Gomez, Aerospace Engineer, Airframe and Mechanical Systems Branch, ANE–171, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, Suite 410, Westbury, New York 11590; telephone (516) 228– 7318; fax (516) 794–5531.

**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 October 28, 2009 (74 FR 55493). That NPRM proposed to correct an unsafe condition for the specified products. The MCAI states:

Investigation into a landing gear retraction problem on a production test flight revealed that, during aircraft pressurization and depressurization cycles, the pressure floor in the main landing gear bay deflects to a small extent. This causes relative misalignment between the [alternate-extension system] AES bypass valve, the downlock assist valve and the summing lever which, in turn, can result in damage to and potential failure of the respective clevis attached to one or both of the valves. Such a clevis failure could remain dormant and, in the subsequent event that use of the AES was required, full landing gear extension may not be achievable.

This directive gives instructions to replace the clevis, with a new part, for both the bypass and the downlock assist valves. It also gives instructions to install new support brackets for both valves, in order to increase the stiffness of the installations and thus prevent future relative misalignment and potential clevis failure. You may obtain further information by examining the MCAI in the AD docket.

Comments

We gave the public the opportunity to participate in developing this AD. We considered the comments received. Support for the NPRM

The Air Line Pilots Association, International (ALPA), supports the NPRM. Request To Allow Repetitive Clevis Replacements in Lieu of Support Bracket Replacement

Comair, Inc., requests that we revise the NPRM to allow repetitive replacement of the bypass valve clevis and downlock assist valve clevis at 6,000-flight-cycle intervals, until the new support brackets have been installed instead of requiring installation of the support brackets at the compliance times specified in paragraph (f)(3) of this AD. Comair, Inc., explains that Bombardier Alert Service Bulletin A670BA–32–022, dated November 8, 2007, established an initial replacement of the clevises along with a repetitive replacement every 6,000 flight cycles. But with the introduction of Part C of Bombardier Alert Service Bulletin A670BA–32–022, Revision A, dated May 1, 2009, Comair, Inc., asserts that the repetitive interval was removed.

Comair, Inc., states that it initiated the compliance with Parts A and B of Bombardier Alert Service Bulletin A670BA–32–022, dated November 8, 2007, in early 2008. Since the initial compliance time, Comair, Inc., states that nearly 2,900 flight cycles have passed and reasons that by the time the NPRM becomes a final rule, 500 or more flight cycles might pass. Comair, Inc., also explains that because of the proposed compliance times specified in paragraphs (f)(3)(ii) and (f)(3)(iii) of the NPRM, the installation of the new support brackets will be required within approximately 2,600 flight cycles (6,000 flight cycles minus 3,400 cycles).

Comair, Inc., asserts that limiting installation of the new support brackets to 2,600 flight cycles instead of 4,500 flight cycles, as proposed by paragraph (f)(3)(i) of the NPRM, penalizes those operators who have taken early action to comply with Bombardier Alert Service Bulletin A670BA–32–022. To compensate for the loss of flight cycles, Comair, Inc., suggests that we revise paragraphs (f)(1) and (f)(2) of the NPRM
to state: ‘‘ * * * Replacement of the clevises each 6,000 flight cycles from the initial replacement, in order to


### 35614 Federal Register / Vol. 75, No. 120 / Wednesday, June 23, 2010 / Rules and Regulations

extend the compliance schedule in paragraph (f)(3) is acceptable. ’’

We do not agree to allow repetitive replacements of the bypass valve clevis and downlock assist valve clevis until the new support bracket is installed. Comair, Inc., noted that the compliance time in paragraph (f)(3)(i) of the NPRM is 4,500 flight cycles; however, the compliance time is 4,500 flight hours. Operators that do the clevis replacement and operators that are not required to replace the clevis both have to comply with the 4,500 flight-hour compliance time to install the support brackets if that compliance time occurs first.

However, we recognize the concern of Comair, Inc., in that the compliance time specified in paragraphs (f)(3)(ii) and (f)(3)(iii) of the NPRM (within 6,000 flight cycles after doing the clevis replacement or within 600 flight cycles after the effective date of this AD) penalizes those operators who have taken early action to comply with replacing the clevis in accordance with Bombardier Alert Service Bulletin A670BA–32–022, dated November 8, 2007. Therefore, we have increased the grace period specified in paragraphs (f)(3)(ii) and (f)(3)(iii) of this AD to allow operators that did the clevis replacement before the effective date of this AD additional time to do the installation of the bracket. We have determined that extending the grace period will not adversely affect safety and meets the intent of the MCAI, Canadian Airworthiness Directive CF– 2009–22, dated May 14, 2009. We have coordinated this change with Transport Canada Civil Aviation (TCCA).

Under the provisions of paragraph (g) of the final rule, we will consider requests for approval of an extension of the compliance time for the installation of the new support brackets if sufficient data are submitted to substantiate that the new compliance time would provide an acceptable level of safety. We have not changed the AD in this regard. Explanation of Change 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 available data, including the comments received, and determined that air safety and the public interest require adopting the AD with the change described previously. We determined that this change will not increase the economic burden on any operator or increase the scope of the AD. Differences Between This AD and the MCAI or Service Information

We have reviewed the MCAI and related service information and, in general, agree with their substance. But we might have found it necessary to use different words from those in the MCAI to ensure the AD is clear for U.S. operators and is enforceable. In making these changes, we do not intend to differ substantively from the information provided in the MCAI and related service information.

We might also have required different actions in this AD from those in the MCAI in order to follow our FAA policies. Any such differences are highlighted in a NOTE within 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 will affect 203 products of U.S. registry. We alsoestimate that it will take about 12 workhours per product to comply with the basic requirements of this AD. The average labor rate is $85 per work-hour. Required parts will cost about $939 per product. Where the service information lists required parts costs that are covered under warranty, we have assumed that there will be no charge for these parts. As we do not control warranty coverage for affected parties, some parties may incur costs higher than estimated here. Based on these figures, we estimate the cost of this AD to U.S. operators to be $397,677, or $1,959 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

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;

2. Is not a ‘‘ significant rule ’’ under the 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.

We prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket. Examining the AD Docket

You may examine the AD docket on the Internet at http:// www.regulations.gov; or in person at the Docket Operations office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains the NPRM, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone (800) 647–5527) is in the **ADDRESSES** section. Comments will be available in the AD docket shortly after receipt. 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:
2010–13–05 Bombardier, Inc.: Amendment 39–16336. Docket No. FAA–2009–0995; Directorate Identifier 2009–NM–123–AD.


### 35615 Federal Register / Vol. 75, No. 120 / Wednesday, June 23, 2010 / Rules and Regulations

Effective Date

(a) This airworthiness directive (AD) becomes effective July 28, 2010.

Affected ADs

(b) None.
Applicability

(c) This AD applies to the airplanes identified in paragraphs (c)(1) and (c)(2) of this AD, certificated in any category.

(1) Bombardier, Inc. Model CL–600–2C10 (Regional Jet Series 700 & 701) airplanes, serial numbers 10003 through 10216 inclusive.

(2) Bombardier, Inc. Model CL–600–2D15 (Regional Jet Series 705) and Model CL–600– 2D24 (Regional Jet Series 900) airplanes, serial numbers 15001 through 15039 inclusive.
Subject

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

Reason

(e) The mandatory continuing airworthiness information (MCAI) states:

Investigation into a landing gear retraction problem on a production test flight revealed that, during aircraft pressurization and depressurization cycles, the pressure floor in the main landing gear bay deflects to a small extent. This causes relative misalignment between the [alternate-extension system] AES bypass valve, the downlock assist valve and the summing lever which, in turn, can result in damage to and potential failure of the respective clevis attached to one or both of the valves. Such a clevis failure could remain dormant and, in the subsequent event that use of the AES was required, full landing gear extension may not be achievable.

This directive gives instructions to replace the clevis, with a new part, for both the bypass and the downlock assist valves. It also gives instructions to install new support brackets for both valves, in order to increase the stiffness of the installations and thus prevent future relative misalignment and potential clevis failure.
Actions and Compliance

(f) Unless already done, do the following actions.

(1) For any bypass valve having part number (P/N) 53342–3, at the applicable time in paragraph (f)(1)(i), (f)(1)(ii), or (f)(1)(iii) of this AD, replace the existing clevis with a new clevis having P/N 2323H037, in accordance with Part A of the Accomplishment Instructions of Bombardier Alert Service Bulletin A670BA–32–022, Revision A, dated May 1, 2009. The replacement is not required if paragraph (f)(3) of this AD has already been done.

(i) If the bypass valve has accumulated 9,400 total flight cycles or fewer as of the effective date of this AD, replace the clevis before the accumulation of 10,000 total flight cycles on the valve.

(ii) If the bypass valve has accumulated more than 9,400 total flight cycles as of the effective date of this AD, replace the clevis within 550 flight hours after the effective date of this AD. (iii) If it is not possible to determine the total flight cycles accumulated on the bypass valve, replace the clevis within 550 flight hours after the effective date of this AD.

(2) For any downlock assist valve having P/N 53341–5, at the applicable time in paragraph (f)(2)(i), (f)(2)(ii), or (f)(2)(iii) of this AD, replace the existing clevis with a new clevis, having P/N 2323H037, in accordance with Part B of the Accomplishment Instructions of Bombardier Alert Service Bulletin A670BA–32–022, Revision A, dated May 1, 2009. The replacement is not required if paragraph (f)(3) of this AD has already been done.

(i) If the valve has accumulated 9,400 total flight cycles or fewer as of the effective date of this AD, replace the clevis before the valve has accumulated 10,000 total flight cycles on the valve.

(ii) If the valve has accumulated more than 9,400 total flight cycles as of the effective date of this AD, replace the clevis within 550 flight hours after the effective date of this AD.

(iii) If it is not possible to determine the total flight cycles accumulated by the downlock assist valve, replace the clevis within 550 flight hours after the effective date of this AD.

(3) At the earliest of the times in paragraphs (f)(3)(i), (f)(3)(ii), and (f)(3)(iii) of this AD, install new support brackets for the bypass valve and downlock assist valve, in accordance with Part C of the Accomplishment Instructions of Bombardier Alert Service Bulletin A670BA–32–022, Revision A, dated May 1, 2009. Installing the support brackets terminates the requirements of paragraphs (f)(1) and (f)(2) of this AD.

(i) Within 4,500 flight hours after the effective date of this AD.

(ii) Within 6,000 flight cycles after accomplishing the actions specified in paragraph (f)(1) of this AD, or 6,000 flight cycles after the effective date of this AD, whichever occurs later.

(iii) Within 6,000 flight cycles after accomplishing the actions specified in paragraph (f)(2) of this AD, or 6,000 flight cycles after the effective date of this AD, whichever occurs later.

(4) Replacing the clevises for the bypass valve and downlock assist valve before the effective date of this AD, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin A670BA– 32–022, dated November 8, 2007, is considered acceptable for compliance with the corresponding actions specified in paragraphs (f)(1) and (f)(2) of this AD.

FAA AD Differences

Note 1: This AD differs from the MCAI and/or service information as follows: No differences.

Other FAA AD Provisions

(g) The following provisions also apply to this AD:

(1) Alternative Methods of Compliance (AMOCs): The Manager, New York Aircraft Certification Office (ACO), ANE–170, 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: Program Manager, Continuing Operational Safety, FAA, New York ACO, 1600 Stewart Avenue, Suite 410, Westbury, New York 11590; telephone 516–228–7300; fax 516– 794–5531. Before using any approved AMOC on any airplane to which the AMOC applies, 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.

(2) Airworthy Product: For any requirement in this AD to obtain corrective actions from a manufacturer or other source, use these actions if they are FAA-approved. Corrective actions are considered FAA-approved if they are approved by the State of Design Authority (or their delegated agent). You are required to assure the product is airworthy before it is returned to service.

(3) Reporting Requirements: For any reporting requirement in this AD, under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq. ), the Office of Management and Budget (OMB) has approved the information collection requirements and has assigned OMB Control Number 2120–0056.

Related Information

(h) Refer to MCAI Canadian Airworthiness Directive CF–2009–22, dated May 14, 2009; and Bombardier Alert Service Bulletin A670BA–32–022, Revision A, dated May 1, 2009; for related information.
Material Incorporated by Reference

(i) You must use Bombardier Alert Service Bulletin A670BA–32–022, Revision A, including Appendix A, dated May 1, 2009, to do the actions required by this AD, unless the AD specifies otherwise. (The revision level is not specified on pages A1 and A2, Appendix A, of this document; those pages are Revision A, dated May 1, 2009.)

(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 Bombardier, Inc., 400 Co ˆ teVertu Road West, Dorval, Que  ́ bec H4S 1Y9, Canada; telephone 514–855–5000; fax 514– 855–7401; e-mail thd.crj@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.

(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.


### 35616 Federal Register / Vol. 75, No. 120 / Wednesday, June 23, 2010 / Rules and Regulations

Issued in Renton, Washington, on June 10,
2010. Jeffrey E. Duven, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 2010–14979 Filed 6–22–10; 8:45 am]

**BILLING CODE 4910–13–P**

**DEPARTMENT OF TRANSPORTATION**

**Federal Aviation Administration**

**14 CFR Part 39**

**[Docket No. FAA–2009–0707; Directorate Identifier 2009–CE–035–AD; Amendment**  **39–16339; AD 2010–13–08]**

**RIN 2120–AA64**

**Airworthiness Directives; Air Tractor, Inc. Models AT–802 and AT–802A**  **Airplanes**

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

**ACTION :**  Final rule.

**SUMMARY :**  We are adopting a new airworthiness directive (AD) to supersede AD 2006–08–09, which applies to all Air Tractor, Inc. (Air Tractor) Models AT–802 and AT–802A airplanes. AD 2006–08–09 currently requires you to repetitively inspect (using the eddy current method) the two outboard fastener holes in both of the wing main spar lower caps at the center splice joint for cracks and repair or replace any cracked spar cap. Since we issued AD 2006–08–09, we have determined we need to clarify the serial numbers (SNs) of the Models AT–802 and AT–802A airplanes affected by that AD. Additionally, we are adding an option of modifying the wing main spar lower caps to extend the safe life limit on the affected airplanes. Consequently, this AD would keep the actions of AD 2006–08–09, clarify the affected SNs, and add a modification option to extend the safe life limit. We are issuing this AD to detect and correct cracks in the wing main spar lower cap at the center splice joint, which could result in failure of the spar cap and lead to wing separation and loss of control of the airplane.

**DATES :**  This AD becomes effective on July 28, 2010.

As of April 21, 2006 (71 FR 19994, April 19, 2006) the Director of the Federal Register approved the incorporation by reference of Snow Engineering Co. Process Specification #197, page 1, revised June 4, 2002; pages 2 through 4, dated February 23, 2001; and page 5, dated May 3, 2002; Snow Engineering Co. Process Specification #204, Rev. C, dated November 16, 2004; Snow Engineering Co. Service Letter #215, page 5, titled ‘‘ 802 Spar Inspection Holes and Vent Tube Mod, ’’ dated November 19, 2003; Snow Engineering Co. Service Letter #240, dated September 30, 2004; Snow Engineering Co. Drawing Number 20975, Sheet 2, Rev. A, dated September 1, 2004; Snow Engineering Co. Drawing Number 20975, Sheet 3, dated January 6, 2005; and Snow Engineering Co. Drawing 20995, Sheet 2, Rev. C, dated September 28, 2004, listed in this AD.

**ADDRESSES :**  For service information identified in this AD, contact Air Tractor, Inc., P.O. Box 485, Olney, Texas 76374; telephone: (940) 564–5616; fax: (940) 564–5612; E-mail: airmail@airtractor.com; Internet: http:// www.airtractor.com.

To view the AD docket, go to U.S. Department of Transportation, Docket Operations, M–30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue, SE., Washington, DC 20590, or on the Internet at http:// www.regulations.gov. The docket number is FAA–2009–0707; Directorate Identifier 2009–CE–035–AD.

**FOR FURTHER INFORMATION CONTACT :**  Andy McAnaul, Aerospace Engineer, 10100 Reunion Pl., Ste. 650, San Antonio, Texas 78216; telephone: (210) 308–3365; fax: (210) 308–3370.

**SUPPLEMENTARY INFORMATION :** 

Discussion

On July 31, 2009, we issued a proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an AD that would apply to all Air Tractor Models AT–802 and AT– 802A airplanes. This proposal was published in the Federal Register as a notice of proposed rulemaking (NPRM) on August 6, 2009 (74 FR 39243). The NPRM proposed to supersede AD 2006– 08–09 to clarify the SNs of the Models AT–802 and AT–802A airplanes affected by that AD. Additionally, we proposed to add an option of modifying the wing main spar lower caps to extend the safe life limit on the affected airplanes.

Comments

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

Conclusion

We have carefully reviewed the available data and determined that air safety and the public interest require adopting the AD as proposed except for minor editorial corrections. We have determined that these minor corrections:

• Are consistent with the intent that was proposed in the NPRM for correcting the unsafe condition; and

• Do not add any additional burden upon the public than was already proposed in the NPRM. Costs of Compliance

We estimate that this AD affects 187 airplanes in the U.S. registry.

We estimate the following costs to do the inspection:

Labor cost Parts cost Total cost per airplane Total cost on U.S. operators

$500 to $800 ...................................... Not applicable ..................................... $500 to $800 $93,500 to $1 49,600

We estimate the following costs to do any necessary repairs for two spars that may be required based on the results of the inspection or the modification as an option. We have no way of determining the number of airplanes that may need this repair:

Labor cost (two spars) Parts cost (two spars) Total cost (two spars) per airplane

225 work-hours × $80 per hour = $18,000 ......................................................................................................... .... $7,500 $25,500