2015-26217. Airworthiness Directives; Bombardier, Inc. Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes. This proposed AD was prompted by reports of chafing damage due to insufficient clearance on the main landing gear (MLG) stabilizer brace, the nacelle A-frame structure, and the adjacent electrical wiring harnesses. An insufficient fillet radius may also exist on certain airplanes. This proposed AD would require, depending on airplane configuration, an inspection of the nacelle A-frame structure for insufficient fillet radius; an inspection for cracking of affected structure, and rework or repair if necessary, and rework of the nacelle A-frame structure; repetitive inspections of the nacelle A-frame structure and the MLG stabilizer brace for insufficient clearance and damage, and repair if necessary, and rework of the nacelle A-frame structure, which would terminate the repetitive inspections; installation of new stop brackets and a shim on each MLG stabilizer brace assembly; and rework of the electrical wiring harnesses in the nacelle area. We are proposing this AD to detect and correct chafing damage and subsequent premature cracking and fracture of the nacelle A-frame structure, which could result in failure of the MLG stabilizer brace and loss of the MLG down-lock indication, which could adversely affect the safe landing of the airplane.

DATES:

We must receive comments on this proposed AD by December 3, 2015.

ADDRESSES:

You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.
• Fax: [phone].
• Mail: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC 20590.
• Hand Delivery: U.S. Department of Transportation, Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this proposed AD, contact Bombardier, Inc., Q-Series Technical Help Desk, 123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; telephone [phone]; fax [phone]; email [e-mail]; Internet http://www.bombardier.com. You may view this referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425-227-1221.

Examining the AD Docket

You may examine the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2015-3986; 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 proposed AD, the regulatory evaluation, any comments received, and other information. The street address for the Docket Operations office (telephone [phone]) is in the ADDRESSES section. Comments will be available in the AD docket shortly after receipt.

FOR FURTHER INFORMATION CONTACT:

Aziz Ahmed, Aerospace Engineer, Airframe and Mechanical Systems Branch, ANE-171, FAA, New York Aircraft Certification Office, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments to an address listed under the ADDRESSES section. Include “Docket No. FAA-2015-3986; Directorate Identifier 2015-NM-057-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD based on those comments.

We will post all comments we receive, without change, to http://www.regulations.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact we receive about this proposed AD.

Discussion

Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued Canadian Airworthiness Directive CF-2014-45, dated December 23, 2014 (referred to after this as the Mandatory Continuing Airworthiness Information, or “the MCAI”), to correct an unsafe condition on certain Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes. The MCAI states:

The aeroplane manufacturer has discovered that an insufficient fillet radius may exist on the flange of the nacelle A-frame structure on certain aeroplanes. There have also been several in-service reports of chafing damage on the main landing gear (MLG) stabilizer brace, the nacelle A-frame structure and its adjacent electrical wiring harnesses due to insufficient clearance.

An insufficient fillet radius and chafing damage on the nacelle A-frame structure and MLG stabilizer brace could lead to premature cracking. Fracture of the nacelle A-frame structure or failure of the MLG stabilizer brace could adversely affect the safe landing of the aeroplane. The damage to the electrical wiring harnesses could result in the loss of the MLG downlock indication.

This [Canadian] AD mandates the inspection and rework of the nacelle A-frame structure, and the rework of the forward MLG stabilizer brace assembly and the electrical harnesses in the nacelle area adjacent to the A-frame structure.

Required actions include, depending on airplane configuration, the following actions:

• A detailed inspection of the nacelle A-frame structure for insufficient fillet radius, an eddy current or fluorescent dye penetrant inspection for cracking of affected structure, and rework or repair if necessary.
• Rework of the left-hand (LH) side and right-hand (RH) side nacelle A-frame structure, including doing a measurement of the clearance between the fasteners/A-frame structure and MLG stabilizer brace assembly and making sure no fouling condition exists, and repair if necessary.
• Repetitive detailed inspections of the nacelle A-frame structure and the MLG stabilizer brace for insufficient clearance and damage, and repair if necessary.
• Rework of the nacelle A-frame structure, including a measurement of the clearance between the A-frame structure and MLG stabilizer brace assembly and a fluorescent dye penetrant inspection or high frequency eddy current inspection for cracking and repair if necessary, which would terminate the repetitive inspections.
• Installation of new stop brackets and a shim on each MLG stabilizer brace assembly.
• Rework of the electrical wiring harnesses in the nacelle area. The rework includes a detailed inspection of the conduit assembly for certain conditions and repair if any condition is found, replacement of damaged conduit, a measurement of the clearance between the stabilizer brace and electrical harness on both LH and RH nacelles to make sure there is 0.100 inch (2.54 millimeters (mm)) minimum clearance between the MLG stabilizer brace, and a check for damage on the A-frame structure and MLG stabilizer brace and repair if necessary.

You may examine the MCAI in the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2015-3986.

Related Service Information Under 1 CFR Part 51

Bombardier has issued the following service information.

• ModSum IS4Q2400028, Revision B, dated June 22, 2012; and ModSum IS4Q240029, Revision A, dated July 6, 2014. These modsums describe procedures for rerouting certain electrical harnesses and installing grommets.
• ModSum IS4Q5450002, Revision B, dated April 30, 2012. This modsum describes procedures for installing specified fasteners on the MLG A-frame, in both the LH and RH nacelles.
• ModSum IS4Q5450003, Revision C, released November 29, 2012. This modsum describes procedures for trimming the horizontal and vertical stiffeners on the MLG A frame in both the LH and RH nacelles.
• Service Bulletin 84-32-112, Revision B, dated September 12, 2014, and Goodrich Service Bulletin 46400-32-102R1, Revision 1, dated June 24, 2013, as referenced in Bombardier Service Bulletin 84-32-112, Revision B, dated September 12, 2014. This service information describes procedures for incorporating Bombardier ModSum 4-902416 by installing new stop brackets and new stop shims for all MLG stabilizer brace assemblies.
• Service Bulletin 84-32-114, Revision A, dated September 18, 2013. This service information describes procedures for rework of the electrical wiring harnesses in the nacelle area. The rework includes a detailed inspection of the conduit assembly for certain conditions and repair, replacement of damaged conduit, a measurement of the clearance to make sure there is 0.100 inch (2.54 mm) minimum clearance between the MLG stabilizer brace, and a check for damage on the A-frame structure and MLG stabilizer brace and repair.
• Service Bulletin 84-54-19, dated April 18, 2013. This service information describes procedures for detailed inspections of the nacelle A-frame structure for insufficient fillet radius, an eddy current or fluorescent dye penetrant inspection for cracking of affected structure, and rework or repair.
• Service Bulletin 84-54-20, Revision B, dated October 2, 2014. This service information describes procedures for detailed inspections of the nacelle A-frame structure and the MLG stabilizer brace for insufficient clearance and damage, and repair. This service information also describes procedures for rework of the nacelle A-frame structure, including a measurement of the clearance between the A-frame structure and MLG stabilizer brace assembly, and a fluorescent dye penetrant inspection or high frequency eddy current inspection for cracking and repair, which would end the inspections.
• Service Bulletin 84-54-21, dated May 9, 2013. This service information describes procedures for rework of the LH side and RH side nacelle A-frame structure, including a measurement of the clearance between the fasteners/A-frame structure and MLG stabilizer brace assembly and to make sure no fouling condition exists, and repair.

This service information is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section of this NPRM.

FAA's Determination and Requirements of this Proposed AD

This product has been approved by the aviation authority of another country, and is approved for operation in the United States. Pursuant to our bilateral agreement with the State of Design Authority, we have been notified of the unsafe condition described in the MCAI and service information referenced above. We are proposing this AD because we evaluated all pertinent information and determined an unsafe condition exists and is likely to exist or develop on other products of the same type design.

Costs of Compliance

We estimate that this proposed AD affects 80 airplanes of U.S. registry.

We also estimate that it would take up to 50 work-hours per product to comply with the basic requirements of this proposed AD. The average labor rate is $85 per work-hour. Required parts would cost $8,452 per product. Based on these figures, we estimate the cost of this proposed AD on U.S. operators to be up to $1,016,160, or $12,702 per product.

We have received no definitive data that would enable us to provide cost estimates for the on-condition actions specified in this proposed AD.

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

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

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

2. Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979);

3. Will not affect intrastate aviation in Alaska; and

4. 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.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Incorporation by reference
• Safety

The Proposed Amendment

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

PART 39—AIRWORTHINESS DIRECTIVES

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

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

§ 39.13

[Amended]

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

Bombardier, Inc.: Docket No. FAA-2015-3986; Directorate Identifier 2015-NM-057-AD.

(a) Comments Due Date

We must receive comments by December 3, 2015.

(b) Affected ADs

None.

(c) Applicability

This AD applies to Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes, certificated in any category, serial numbers (S/Ns) 4001 through 4431 inclusive.

(d) Subject

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

(e) Reason

This AD was prompted by reports of chafing damage due to insufficient clearance on the main landing gear (MLG) stabilizer brace, the nacelle A-frame structure, and the adjacent electrical wiring harnesses. An insufficient fillet radius might also exist on certain airplanes. We are issuing this AD to detect and correct chafing damage and subsequent premature cracking and fracture of the nacelle A-frame structure, which could result in failure of the MLG stabilizer brace and loss of the MLG down-lock indication, which could adversely affect the safe landing of the airplane.

(f) Compliance

Comply with this AD within the compliance times specified, unless already done.

(g) Inspection, Corrective Actions if Necessary, and Rework

For airplanes having S/Ns 4001 through 4055 inclusive: Do the actions required by paragraphs (g)(1) and (g)(2) of this AD.

(1) Within 600 flight hours or 100 days after the effective date of this AD, whichever occurs first: Do a detailed inspection of the left-hand (LH) side and right-hand (RH) side nacelle A-frame structure for insufficient fillet radius, in accordance with “Part A—Inspection” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-19, dated April 18, 2013. If an insufficient fillet radius exists, before further flight, do an eddy current or fluorescent dye penetrant inspection for cracking, in accordance with “Part A—Inspection” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-19, dated April 18, 2013.

(i) If any cracking is found: Before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or Transport Canada Civil Aviation (TCCA); or Bombardier, Inc.'s TCCA Design Approval Organization (DAO).

(ii) If no cracking is found: Before further flight, rework the structure, in accordance “Part B—Rectification” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-19, dated April 18, 2013.

(2) Within 6,000 flight hours or 36 months after the effective date of this AD, whichever occurs first: Rework the LH side and RH side nacelle A-frame structure, including doing a measurement of the clearance between the fasteners/A-frame structure and MLG stabilizer brace assembly and making sure no fouling condition exists, in accordance with paragraph 3.B. “Procedure,” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-21, dated May 9, 2013. If the clearance is found to be less than 0.100 inch (2.54 millimeters (mm)) between the fasteners/A-frame structure and MLG stabilizer brace assembly after the rework is done, or a fouling condition exists during the extension of the MLG after rework is done, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.

(h) Repetitive Inspections and Corrective Actions if Necessary

For airplanes having S/Ns 4056 through 4426 inclusive: Within 600 flight hours or 100 days after the effective date of this AD, whichever occurs first: Do a detailed inspection of the LH side and RH side nacelle A-frame structure and upper surface of the MLG stabilizer brace for insufficient clearance and damage (e.g., cracking), in accordance with “Part A—Inspection,” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-20, Revision B, dated October 2, 2014. If no damage is found and clearance is sufficient: Repeat the inspection thereafter at intervals not to exceed 600 flight hours until the terminating action required by paragraph (i) of this AD has been done.

(1) If a clearance less than 0.100 inch (2.54 mm) exists between the A-frame structure and the MLG stabilizer brace assembly in the retracted position, after the rework is done, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.

(2) If any damage is found: Before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.

(i) Terminating Action for Certain Airplanes

For airplanes having S/Ns 4056 through 4426 inclusive: Within 6,000 flight hours or 36 months after the effective date of this AD, whichever occurs first; Rework the LH side and RH side nacelle A-frame structure, including doing a measurement of the clearance between the A-frame structure and MLG stabilizer brace assembly and doing a fluorescent dye penetrant inspection or high frequency eddy current inspection for cracking, in accordance with “Part B-Rework,” of the Accomplishment Instructions of Bombardier Service Bulletin 84-54-20, Revision B, dated October 2, 2014. Accomplishment of the actions required by this paragraph terminates the repetitive inspections required by paragraph (h) of this AD.

(1) If a clearance less than 0.100 inch (2.54 mm) exists between the A-frame structure and the MLG stabilizer brace assembly in the retracted position after the rework is done, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.

(2) If any cracking is found: Before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.

(j) Modification of MLG Stabilizer Brace Assembly

For airplanes having S/Ns 4001 through 4431 inclusive with a MLG stabilizer brace assembly having part number 46400-27 installed: Within 6,000 flight hours or 36 months after the effective date of this AD, whichever occurs first; incorporate Bombardier ModSum 4-902416 by installing new stop brackets and a new shim on each MLG stabilizer brace assembly, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-32-112, Revision B, dated September 12, 2014, and Goodrich Service Bulletin 46400-32-102R1, Revision 1, dated June 24, 2013, as referenced in Bombardier Service Bulletin 84-32-112, Revision B, dated September 12, 2014.

(k) Rework of the Electrical Wiring Harnesses

For airplanes having S/Ns 4001 through 4411 inclusive: Within 6,000 flight hours or 36 months after the effective date of this AD, whichever occurs first; rework the LH and RH sides of the electrical wiring harnesses in the nacelle area adjacent to the A-frame structure, including doing the actions specified in paragraphs (k)(1) through (k)(4) of this AD, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 84-32-114, Revision A, dated September 18, 2013. If any damage is found on the A-frame structure or MLG stabilizer brace, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.

(1) Doing a detailed inspection of the conduit assembly for the conditions specified in Bombardier Service Bulletin 84-32-114, Revision A, dated September 18, 2013, and, before further flight, repairing if any condition is found.

(2) Replacing damaged conduit.

(3) Measuring the clearance between the stabilizer brace and electrical harness on both LH and RH nacelles to make sure there is 0.100 inch (2.54 mm) minimum clearance between the MLG stabilizer brace.

(4) Checking for damage on the A-frame structure and MLG stabilizer brace.

(l) Optional Installations

(1) Installing specified fasteners on the MLG A-frame, in both LH and RH nacelles, in accordance with Bombardier ModSum IS4Q5450002, Revision B, dated April 30, 2012, is acceptable for compliance with the actions specified in paragraph (g) of this AD, provided the actions specified in Bombardier ModSum IS4Q5450002 are done within the compliance time specified in paragraph (g) of this AD, except where ModSum IS4Q5450002, Revision B, dated April 30, 2012, specifies to contact Bombardier for reduced clearances, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.

(2) Trimming the horizontal and vertical stiffeners on MLG A-frame in both LH and RH nacelles, in accordance with Bombardier ModSum IS4Q5450003, Revision C, released November 29, 2012, is acceptable for compliance with the actions specified in paragraph (i) of this AD, provided the actions specified in Bombardier ModSum IS4Q5450003 are done within the compliance time specified in paragraph (i) of this AD, except where ModSum IS4Q5450003, Revision C, released November 29, 2012, specifies to contact Bombardier for reduced clearances, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.

(3) Rerouting certain electrical harnesses and installing grommets, in accordance with Bombardier ModSum IS4Q2400028, Revision B, dated June 22, 2012 (for S/Ns 4001 through 4098 inclusive) or Bombardier ModSum IS4Q2400029, Revision A, dated July 6, 2014 (for S/Ns 4090 through 4411 inclusive), is acceptable for compliance with the actions specified in paragraph (k) of this AD, provided the actions specified in the applicable modsum are done within the compliance time specified in paragraph (k) of this AD, except where Bombardier ModSum IS4Q2400028, Revision B, dated June 22, 2012; and Bombardier ModSum IS4Q2400029, Revision A, dated July 6, 2014; specify to contact Bombardier to report stabilizer brace or structural damaged findings, before further flight, repair using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO.

(m) Credit for Previous Actions

(1) This paragraph provides credit for actions required by paragraph (i) of this AD, if those actions were performed before the effective date of this AD using the applicable service information specified in paragraph (m)(1)(i) or (m)(1)(ii) of this AD. This service information is not incorporated by reference in this AD.

(i) Bombardier Service Bulletin 84-54-20, dated April 25, 2013.

(ii) Bombardier Service Bulletin 84-54-20, Revision A, dated April 9, 2014.

(2) This paragraph provides credit for actions required by paragraph (j) of this AD, if those actions were performed before the effective date of this AD using the applicable service information specified in paragraph (m)(2)(i) or (m)(2)(ii) of this AD. This service information is not incorporated by reference in this AD.

(i) Bombardier Service Bulletin 84-32-112, dated December 20, 2012.

(ii) Bombardier Service Bulletin 84-32-112, Revision A, dated April 16, 2014.

(3) This paragraph provides credit for actions required by paragraph (k) of this AD, if those actions were performed before the effective date of this AD using Bombardier Service Bulletin 84-32-114, dated June 6, 2013. This service information is not incorporated by reference in this AD.

(n) Other FAA AD Provisions

The following provisions also apply to this AD:

(1) Alternative Methods of Compliance (AMOCs): The Manager, New York ACO, ANE-170, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the ACO, send it to ATTN: Program Manager, Continuing Operational Safety, FAA, New York ACO, 1600 Stewart Avenue, Suite 410, Westbury, NY 11590; telephone [phone]; fax [phone]. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office. The AMOC approval letter must specifically reference this AD.

(2) Contacting the Manufacturer: For any requirement in this AD to obtain corrective actions from a manufacturer, the action must be accomplished using a method approved by the Manager, New York ACO, ANE-170, FAA; or TCCA; or Bombardier, Inc.'s TCCA DAO. If approved by the DAO, the approval must include the DAO-authorized signature.

(o) Related Information

(1) Refer to Mandatory Continuing Airworthiness Information (MCAI) Canadian Airworthiness Directive CF-2014-45, dated December 23, 2014, for related information. This MCAI may be found in the AD docket on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2015-3986.

(2) For service information identified in this AD, contact Bombardier, Inc., Q-Series Technical Help Desk, 123 Garratt Boulevard, Toronto, Ontario M3K 1Y5, Canada; telephone [phone]; fax [phone]; email [e-mail]; Internet http://www.bombardier.com. You may view this service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425-227-1221.

Issued in Renton, Washington, on October 5, 2015.

Jeffrey E. Duven,

Manager, Transport Airplane Directorate, Aircraft Certification Service.