Discussion
We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Airbus SAS Model A318 and A319 series airplanes; Model A320-211, -212, -214, -231, -232, and -233 airplanes; and Model A321-111, -112, -131, -211, -212, -213, - 231, and -232 airplanes. The NPRM published in the Federal Register on July 10, 2018 (83 FR 31911). The NPRM was prompted by reports of false RAs from certain TCASs. The NPRM proposed to require modification or replacement of certain TCAS processors.
We are issuing this AD to address the occurrence of false RAs from the TCAS, which could lead to a loss of separation from other airplanes, possibly resulting in a mid-air collision.
The European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2017-0196, dated October 5, 2017 (referred to after this as the Mandatory Continuing Airworthiness Information, or ``the MCAI''), to correct an unsafe condition for certain Airbus SAS Model A318 and A319 series airplanes; Model A320-211, -212, -214, -231, -232, and -233 airplanes; and Model A321-111, -112, -131, -211, -212, -213, -231, and -232 airplanes. The MCAI states:
Since 2012, a number of false TCAS resolution advisories (RA) have been reported by various European Air Navigation Service Providers. EASA has published certification guidance material for collision avoidance systems (AMC 20-15) which defines a false TCAS RA as an RA that is issued, but the RA condition does not exist. It is possible that more false (or spurious) RA events have occurred, but were not recorded or reported. The known events were mainly occurring on Airbus single-aisle (A320 family) aeroplanes, although several events have also occurred on Airbus A330 aeroplanes. Investigation determined that the false RAs are caused on aeroplanes with a Honeywell TPA-100B TCAS processor installed, P/N [part number] 940-0351-001. This was caused by a combination of three factors: (1) Hybrid surveillance enabled; (2) processor connected to a hybrid GPS [global positioning system] source, without a direct connection to a GPS source; and (3) an encounter with an intruder aeroplane with noisy (jumping) ADS-B Out position.
EASA previously published Safety Information Bulletin (SIB) 2014-33 to inform owners and operators of affected aeroplanes about this safety concern. At that time, the false RAs were not considered an unsafe condition. Since the SIB was issued, further events have been reported, involving a third aeroplane.
This condition, if not corrected, could lead to a loss of separation with other aeroplanes, possibly resulting in a mid-air collision.
Prompted by these latest findings, and after review of the available information, EASA reassessed the severity and rate of occurrence of false RAs and has decided that mandatory action must be taken to reduce the rate of occurrence, and the risk of loss of separation with other aeroplanes. Honeywell International Inc. published Service Bulletin
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(SB) 940-0351-34-0005 [Publication Number D201611000002] to provide instructions for an upgrade, introducing software version 05/01, changing the processor unit to P/N 940-0351-005.
EASA previously issued AD 2017-0091 (later revised) to address the unsafe condition on aeroplanes that had the P/N 940-0351-001 processor installed by Airbus major change or SB. However, part of the fleet had the same P/N installed by STC [supplemental type certificate]. The relevant STC approval holders (see section Remarks of this [EASA] AD for contact details) have been notified and modification instructions (see section Ref. Publications of this [EASA] AD) can be obtained from those companies.
For the reason described above, this [EASA] AD requires modification or replacement of Honeywell TPA-100B P/N 940-0351-001 TCAS processors. This [EASA] AD also prohibitsinstallation of those processors on post-mod aeroplanes.
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-2018- 0589.
Comments
We gave the public the opportunity to participate in developing this final rule. The following presents the comment received on the NPRM and the FAA's response to that comment.
Request To Withdraw the NPRM
Delta Air Lines (DAL) observed that the proposed AD is redundant to AD 2018-06-01, Amendment 39-19221 (83 FR 12852, March 26, 2018) (``AD 2018-06-01''), because they both address the modification or replacement of a TCAS processor. We infer a request to withdraw the NPRM.
We disagree because this AD pertains to aircraft that have had their TCAS processor modified by an FAA-validated supplemental type certificate (STC), whereas AD 2018-06-01 pertains to the aircraft type certificate (TC) and the TCAS processor modification required by that AD does not include airplanes modified by an FAA STC. We have made no change to this AD in this regard.
Conclusion
We reviewed the relevant data, considered the comment received, and determined that air safety and the public interest require adopting this final rule as proposed, except for minor editorial changes. We have determined that these minor changes:
Are consistent with the intent that was proposed in the NPRM for addressing the unsafe condition; and
Do not add any additional burden upon the public than was already proposed in the NPRM.
Related Service Information Under 1 CFR Part 51
H4 Aerospace has issued Service Bulletin H4ASB009, Issue 1, dated September 18, 2017; and PMV Engineering has issued Service Bulletin AVI-00690-SB-S99-R01, Revision 01, dated October 5, 2017. This service information, provided by the applicable design change FAA STC approval holders, describes the modification or replacement of the Honeywell TPA-100B TCAS processor. These documents are distinct because they apply to airplanes having different STCs installed. 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.
Other Related Service Information
Honeywell International, Inc., has issued Service Bulletin 940- 0351-34-0005, Revision 2, dated December 1, 2017. This service information describes procedures for updating the software of the Honeywell TPA-100B TCAS processor either on the airplane or at an authorized service center.
Costs of Compliance
We estimate that this AD affects 1209 airplanes of U.S. registry.
We estimate the following costs to comply with this AD:
Estimated Costs ----------------------------------------------------------------------------------------------------------------
Cost on U.S.
Action Labor cost Parts cost Cost per productoperators ---------------------------------------------------------------------------------------------------------------- Modification................... 1 work-hour x $85 per Up to $1,623..... Up to $1,708..... Up to $2,064,972.
hour = $85. ----------------------------------------------------------------------------------------------------------------
Estimated Costs for Optional Actions ----------------------------------------------------------------------------------------------------------------
Cost per
Action Labor cost Parts cost product ---------------------------------------------------------------------------------------------------------------- Replacement................................ 1 work-hour x $85 per hour = $85... $121,993 $122,078 ----------------------------------------------------------------------------------------------------------------
According to the manufacturer, some of the costs of this AD 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, 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.
This AD is issued in accordance with authority delegated by the Executive Director, Aircraft Certification Service, as authorized by FAA Order 8000.51C. In accordance with that order, issuance of ADs is normally a function of the Compliance and Airworthiness Division, but during this transition period, the Executive Director has delegated the authority to issue ADs applicable to transport category airplanes and associated appliances to the Director of the System Oversight Division.
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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, Icertify 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.