Discussion
The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, has issued AD No. 2017-0090, dated May 17, 2017 (referred to after this as ``the MCAI''), to correct an unsafe condition for Diamond Aircraft Industries GmbH Model DA 42 and DA 42 M airplanes. The MCAI states:
Two cases were reported of uncommanded engine in-flight shutdown (IFSD) on DA 42 aeroplanes. Subsequent investigations identified that these occurrences were due to failure of the propeller regulating valve, caused by hot exhaust gases coming from fractured engine exhaust pipes. The initiating cracks on the exhaust pipes were not detected during previous inspections, since those exhaust pipes are equipped with non-removable heat shields that do not allow inspection for certain sections of the exhaust pipe.
This condition, if not corrected, could lead to further cases of IFSD or overheat damage, possibly resulting in a forced landing, with consequent damage to the aeroplane and injury to occupants.
To address this potential unsafe condition, Diamond Aircraft Industries (DAI) developed an exhaust pipe without a directly attached integral heat shield that allows visual inspection over the entire exhaust pipe length. DAI issued Mandatory Service Bulletin (MSB) 42-120 and relevant Working Instruction (WI) WI-MSB 42-120, providing instructions to install the modified exhaust pipes. As an interim measure, an additional bracket was designed to hold the exhaust pipe in place in case of a pipe fracture. EASA issued AD 2016-0156 (later revised), requiring replacement of the exhaust pipes with pipes having the new design, or installation of the additional brackets.
Since EASA AD 2016-0156R1 was issued, cracks were found during inspection on modified exhaust pipes. Further investigation determined that, with the modified exhaust pipe design, vibration leads to cracking.
To address thispotential unsafe condition, DAI published MSB 42-129 providing instructions for inspection of modified exhaust pipes.
For the reasons described above, this AD retains the requirements of EASA AD 2016-0156R1, which is superseded, and requires repetitive inspections of modified exhaust pipes and, depending on findings, repair or replacement. This AD is considered interim action and further AD action may follow upon availability of an improved exhaust pipe design.
You may examine the MCAI on the Internet at http://www.regulations.gov by searching for and locating Docket No. FAA-2017- 0506.
Related Service Information Under 1 CFR Part 51
Diamond Aircraft Industries GmbH has issued Mandatory Service Bulletin MSB-42-129, dated May 17, 2017, and Work Instruction WI-OSB- 42-122, Revision 2, dated June 24, 2016. Mandatory Service Bulletin MSB-42-129, dated May 17, 2017, describes procedures for inspecting the DAI part number (P/N) D60-9078-06-01_01 and Technify P/N 52-7810-H0014 01 engine exhaust pipes. Work Instruction WI-OSB-42-122, Revision 2, dated June 24, 2016, describes procedures for (among other things) replacing the engine exhaust pipes. 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 the final rule.
FAA's Determination and Requirements of the 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 this State of Design Authority, they have notified us of the unsafe condition described in the MCAI and service information referenced above. We are issuing this AD because we evaluated all information provided by the State of Design Authority and determined the unsafe condition exists and is likely to exist or develop on other products of the same type design.
Differences Between the AD and MCAI
The MCAI allows for either replacement or repair if a cracked exhaust pipe is found during an inspection. This AD will only allow for replacement. If there were to become a parts availability issue at some time, we would consider the welding repair as an alternative method of compliance.
In addition, the MCAI supersedes the previous EASA AD 2016-0156R1, which introduced the DAI part number (P/N) D60-9078-06-01_01 and Technify P/N 52-7810-H0014 01 engine exhaust pipes that are the subject of this AD. The FAA is not superseding the corresponding AD 2017-01-12, Amendment 39-18779 (82 FR 5359; January 18, 2017) because there were other options in that AD that would not be affected by this action. Thus AD 2017-01-12 establishes the baseline for the applicability of this AD, and if any of the affected exhaust pipes were installed per AD 2017-01-12 they would be subject to the actions of this AD action.
The airplane models affected by the MCAI are the Models DA42 and DA 42 M. Only the DA 42 is type certificated in the United States so this AD action will only affect the Model DA 42 airplanes.
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FAA's Determination of the Effective Date
An unsafe condition exists that requires the immediate adoption of this AD. The FAA has found that the risk to the flying public justifies waiving notice and comment prior to adoption of this rule because the affected engine exhaust pipes could crack and cause hot gases to leak from fractured exhaust pipes and lead to an uncommanded engine in- flight shutdown. Therefore, we determined that notice and opportunity for public comment before issuing this AD are impracticable and that good cause exists for making this amendment effective in fewer than 30 days.
Comments Invited
This AD is a final rule that involves requirements affecting flight safety, and we did not precede it by notice and opportunity for public comment. We invite you to send any written relevant data, views, or arguments about this AD. Send your comments to an address listed under the ADDRESSES section. Include ``Docket No. FAA-2017-0506; Directorate Identifier 2017-CE-019-AD'' at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this AD. We will consider all comments received by the closing date and may amend this AD because of 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 AD.
Costs of Compliance
We estimate that this AD will affect 130 products of U.S. registry. We also estimate that it would take about 2 work-hours per product to comply with the basic requirements of this AD. The average labor rate is $85 per work-hour.
Based on these figures, we estimate the cost of the AD on U.S. operators to be $22,100, or $170 per product.
In addition, we estimate that any necessary follow-on actions would take about 2 work-hours and require parts costing $2,100, for a cost of $2,270 per product. We have no way of determining the number of products that may need these actions.
According to the design approval holder, some of the costs of this AD (cost of parts) may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all costs in our cost estimate.
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, SubpartIII, 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 that 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),
(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.