E6-9714. Airworthiness Directives; Fokker Model F27 Mark 500 Airplanes

AGENCY:

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

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for all Fokker Model F27 Mark 500 airplanes. This proposed AD would require an inspection to determine whether certain main landing gear (MLG) drag stay units (DSUs) are installed. This proposed AD would also require an ultrasonic inspection to determine if certain tubes are installed in the affected DSUs of the MLG, and related investigative/corrective actions if necessary. This proposed AD results from a report that, due to fatigue cracking from an improperly machined radius of the inner tube, a drag stay broke, and, consequently, led to the collapse of the MLG during landing. We are proposing this AD to prevent such fatigue cracking, which could result in reduced structural integrity or collapse of the MLG.

DATES:

We must receive comments on this proposed AD by July 21, 2006.

ADDRESSES:

Use one of the following addresses to submit comments on this proposed AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590.
• Fax: [phone].
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

Contact Fokker Services B.V., P.O. Box 231, 2150 AE Nieuw-Vennep, the Netherlands, for service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Tom Rodriguez, Aerospace Engineer, International Branch, ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed in the ADDRESSES section. Include the docket number “FAA-2006-25086; Directorate Identifier 2006-NM-019-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the proposed AD. We will consider all comments received by the closing date and may amend the proposed AD in light of those comments.

We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this proposed AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Examining the Docket

You may examine the AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone [phone]) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Discussion

The Civil Aviation Authority—The Netherlands (CAA-NL), which is the airworthiness authority for the Netherlands, notified us that an unsafe condition may exist on certain Fokker Model F27 Mark 500 airplanes. The CAA-NL advises that it has received a report that, due to a broken drag stay, the main landing gear (MLG) on one airplane collapsed during landing. The broken drag stay is attributed to fatigue cracking, which originated at the lower side of a transition from a smaller internal diameter on the upper piece to a larger internal diameter on the lower piece. The apparent cause of such fatigue cracking has been attributed to an improperly machined radius of the inner tube of the drag stay. This condition, if not corrected, could result in reduced structural integrity or collapse of the MLG.

The CAA-NL states that Dutch airworthiness directive BLA 93-169/2 (A), dated April 29, 1994, was issued following a similar incident to address the identified unsafe condition on all F27 airplanes. However, the related Fokker Service Bulletin F27/32-167, dated November 19, 1993, contained a statement that may have led to confusion whether Model F.27 Mark 500 airplanes were affected by the actions specified in the service bulletin. Thus, Model F27 Mark 500 airplanes may be operating without fully complying with actions necessary to address the identified unsafe condition.

Other Relevant Rulemaking

On February 7, 1997, we issued AD 97-04-08, amendment 39-9932 (62 FR 7924, February 21, 1997), for certain Fokker Model F27 Mark 050, 100, 200, 300, 400, 600, and 700 airplanes. That AD is parallel to Dutch airworthiness directive BLA 93-169/2 (A), dated April 29, 1994, and does not include Model F27 Mark 500 airplanes in its applicability. AD 97-04-08 requires an ultrasonic inspection to determine if certain tubes are installed in the drag stay units of the main landing gear (MLG), and various follow-on actions. That AD resulted from a report that, due to fatigue cracking from an improperly machined radius of the inner tube, a drag stay broke, and, consequently, led to the collapse of the MLG during landing. We issued that AD to prevent such fatigue cracking, which could result in reduced structural integrity or collapse of the MLG.

Relevant Service Information

Fokker Services B.V has issued Fokker Service Bulletin F27/32-171, dated December 16, 2004 (for Model F27 Mark 500 airplanes). The service bulletin describes procedures for performing an inspection of the MLG drag stay units (DSUs) in accordance with Dowty Aerospace Landing Gear Service Bulletin 32-82W, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; or Dowty Aerospace Landing Gear Service Bulletin 32-169B, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993.

Dowty Aerospace Landing Gear Service Bulletins 32-82W and 32-169B describe procedures for performing an ultrasonic inspection to determine if a tube having part number (P/N) 200485300 with a straight bore, or a tube having P/N 200259300 with a change in section (stepped bore), is installed in the DSUs of the MLG. The service bulletins also describe procedures for related investigative actions and corrective actions, including ultrasonic inspection for cracking of the DSUs, rework and re-identification of certain tubes, replacement of certain DSUs with new/re-identified DSUs, and repetitive ultrasonic inspections of certain DSUs. Both service bulletins include the ultrasonic inspection to determine P/Ns for DSUs having P/N 200485001. Service bulletin 32-82W also addresses the ultrasonic inspection for DSUs having P/N 200684001. Service Bulletin 32-169B also addresses the ultrasonic inspection for DSUs having P/N 200261001.

CAA-NL mandated the service information and issued airworthiness directive NL-2005-003, dated April 29, 2005, to ensure the continued airworthiness of these airplanes in the Netherlands.

FAA's Determination and Requirements of the Proposed AD

This airplane model is manufactured in the Netherlands and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, CAA-NL has kept the FAA informed of the situation described above. We have examined the CAA-NL's findings, evaluated all pertinent information, and determined that we need to issue an AD for airplanes this type design that are certificated for operation in the United States.

Therefore, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously.

Costs of Compliance

The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs

Action	Work hours	Average labor rate per hour	Cost per airplane	Number of U.S.-registered airplanes	Fleet cost
Inspection	2	$80	$160	7	$1,120

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 have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify that the proposed regulation:

1. Is not a “significant regulatory action” under Executive Order 12866;

2. Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 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 proposed AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:

PART 39—AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

§ 39.13

[Amended]

2. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

Fokker Services B.V.: Docket No. FAA-2006-25086; Directorate Identifier 2006-NM-019-AD.

Comments Due Date

(a) The FAA must receive comments on this AD action by July 21, 2006.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all Fokker Model F27 Mark 500 airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from a report that, due to fatigue cracking from an improperly machined radius of the inner tube, a drag stay broke, and, consequently, led to the collapse of the MLG during landing. We are issuing this AD to prevent such fatigue cracking, which could result in reduced structural integrity or collapse of the MLG.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Inspections of the DSUs

(f) Within 60 days after the effective date of this AD: Inspect main landing gear (MLG) drag stay units (DSU) to determine whether Dowty Aerospace is the manufacturer and before further flight inspect Dowty Aerospace MLG DSUs to determine whether part number (P/N) 200261001, 200261002, 200485001, 200485002, 200684001, or 200684002 is installed. A review of airplane maintenance records is acceptable in lieu of these inspections if the manufacturer and P/N of the MLG DSU can be conclusively determined from that review. For airplanes equipped with MLG DSUs other than Dowty Aerospace MLG DSUs, and for airplanes equipped with Dowty Aerospace MLG DSUs having P/Ns other than P/N 200261001, 200261002, 200485001, 200485002, 200684001, and 200684002, no further action is required by this AD, except as specified in paragraph (k) of this AD.

(g) For airplanes equipped with DSUs having P/N 200261001, 200485001, or 200684001: Within 60 days after the effective date of this AD, perform an ultrasonic inspection to determine if a tube having P/N 200485300 with a straight bore, or a tube having P/N 200259300 with a change in section (stepped bore), is installed on the DSUs of the MLG, in accordance with the Accomplishment Instructions of Fokker Service Bulletin F27/32-171, dated December 16, 2004.

Note 1:

Fokker Service Bulletin F27/32-171, dated December 16, 2004, references Dowty Aerospace Landing Gear Service Bulletin 32-82W, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; and Dowty Aerospace Landing Gear Service Bulletin 32-169B, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; as applicable, as appropriates sources of service information for inspecting MLG DSUs.

(h) If any tube having P/N 200485300 with a straight bore is found installed during the inspections required by paragraph (g) of this AD: Before further flight, re-identify the DSU with P/N 200261004, 200485004, or 200684004, in accordance with the Accomplishment Instructions of Dowty Aerospace Landing Gear Service Bulletin 32-82W, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; or Dowty Aerospace Landing Gear Service Bulletin 32-169B, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; as applicable. After re-identifying the DSU, no further action is required by this AD for that DSU; however airplanes are still subject to the requirements specified in paragraph (k) of this AD.

(i) If any tube having P/N 200259300 with a change in section (stepped bore) is found installed during the inspection required by paragraph (g) of this AD: Before further flight, re-identify the DSU in accordance with paragraphs 2.A.(4)(a) and 2.A.(4)(b) of the Accomplishment Instructions Dowty Aerospace Landing Gear Service Bulletin 32-82W, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; or Dowty Aerospace Landing Gear Service Bulletin 32-169B, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; as applicable. Following accomplishment of the re-identification, before further flight, do the inspection specified in paragraph (j) of this AD.

Ultrasonic Inspection for Cracking

(j) For airplanes equipped with re-identified DSUs having 200261002, 200485002, 200684002, 200261003, 200485003, or 200684003: Within 60 days after the effective date of this AD, perform an ultrasonic inspection to detect cracking in the re-identified DSUs, in accordance with the Accomplishment Instructions of Dowty Aerospace Landing Gear Service Bulletin 32-82W, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; or Dowty Aerospace Landing Gear Service Bulletin 32-169B, Revision 2, including Appendix A, dated July 29, 1994, and including Appendix B, Revision 1, dated November 10, 1993; as applicable.

(1) For airplanes equipped with any DSU re-identified as P/N 200684003, 200261003, or 200485003: If no crack is detected, no further action is required by this AD for that DSU; however airplanes are still subject to the requirements specified in paragraph (k) of this AD.

(2) For airplanes equipped with any DSU re-identified as P/N 200684002, 200261002, or 200485002: If no crack is detected, do the actions specified in paragraphs (j)(2)(i) and (j)(2)(ii) of this AD.

(i) Repeat the ultrasonic inspection required by paragraph (j) of this AD thereafter at intervals not to exceed 1,500 flight cycles until the actions specified in paragraph (j)(2)(ii) of this AD are done.

(ii) At the next MLG overhaul but no later than 12,000 flight cycles after the effective date of this AD, rework and re-identify the DSU as P/N 200261003, 200485003, or 200684003, as applicable, in accordance with the applicable service bulletin.

(3) If any crack is detected and the crack signal indication of any DSU tube is greater than or equal to 80 percent, before further flight, replace the DSU with a re-identified DSU having P/N 200261004, 200485004, 200684004, 200261003, 200485003, or 200684003, in accordance with the applicable service bulletin.

(4) If any crack is detected and the crack signal indication of any DSU tube is greater than zero percent but less than 80 percent, do the actions specified in paragraphs (j)(4)(i) and (j)(4)(ii) of this AD.

(i) Repeat the ultrasonic inspection required by paragraph (j) of this AD thereafter at intervals not to exceed 1,500 flight cycles until the actions specified in paragraph (j)(4)(ii) of this AD are done.

(ii) At the next MLG overhaul but no later than 12,000 flight cycles after the effective date of this AD, replace the DSU with a DSU having P/N 200261004, 200485004, 200684004, 200261003, 200485003, or 200684003, in accordance with the applicable service bulletin.

Parts Installation

(k) As of the effective date of this AD, no person may install a MLG DSU, P/N 200261001, 200261002, 200485001, 200485002, 200684001, or 200684002, on any airplane, except as specified in paragraph (i) of this AD.

Alternative Methods of Compliance (AMOCs)

(l)(1) The Manager, International Branch, ANM-116, Transport Airplane Directorate, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

Related Information

(m) Dutch airworthiness directive NL-2005-003, dated April 29, 2005, also addresses the subject of this AD.

Issued in Renton, Washington, on June 14, 2006.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.