We have received reports indicating that, on airplanes equipped with the Honeywell Primus Epic system, all information on all cockpit display units may be lost (blank screens) or may become simultaneously invalid during flight. On Cessna Model 680 airplanes, this condition has been attributed to a failure of the master network interface controller (NIC) in the Honeywell Primus Epic system to synchronize with NICs that control the avionics system communication bus (ASCB). Attempts by all of the NICs to re-synchronize disables all ASCB data. The synchronization process can be delayed or worsened by a failure of any ASCB. This condition, if not corrected, could result in the simultaneous loss of data from all four cockpit display units, and loss of primary navigation instruments, autopilot, flight director, master caution/warning lights, aural warnings, global positioning system position information, and air data and altitude information to non-avionics systems.These losses could reduce the flightcrew's situational awareness, increase flightcrew workload, and consequently reduce the ability to maintain safe flight of the airplane.
Other Relevant Rulemaking
We have determined that, since the Honeywell Primus Epic system is also installed on Dassault Model Falcon 2000EX and 900EX series airplanes, Gulfstream Model GV-SP series airplanes, and Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model ERJ 170 series airplanes, those airplanes are subject to an unsafe condition similar to that addressed in this AD. In light of that determination, we issued the ADs listed in the following table to address the unsafe condition on those airplane models.
Related ADs
Airplane
AD citation
Dassault Model Falcon 2000EX and 900EX series airplanes
AD 2005 04 15, amendment 39 13987 (70 FR 9853, March 1, 2005).
Gulfstream Model GV SP series airplanes
AD 2005 04 06, amendment 39 13978 (70 FR 7847, February 16, 2005).
EMBRAERModel ERJ 170 series airplanes
AD 2004 26 12, amendment 39 13924 (69 FR 78300, December 30, 2004).
Relevant Service Information
We have reviewed Cessna Service Bulletin SB680-34-03, including Attachment, Revision 1, dated March 18, 2005. The service bulletin describes procedures for performing repetitive tests of the avionics standard communication bus (ASCB) for any failures; accomplishing corrective action if any failure is found during the ASCB test; and installing hardware and avionics software upgrades. The corrective action for ASCB test failures includes fixing any wiring problems, replacing parts, and correcting computer configurations. The hardware and avionics software upgrades include:
Installing a software upgrade of the Honeywell Primus Epic system;
Replacing the horizontal stabilizer trim actuator with a new, improved actuator;
Modifying certain wiring associated with the actuator; and
Replacing two printed circuit boards (PCBs) with new, improved PCBs.
We have also reviewed Cessna Temporary Changes (TC) 68FM TC-R03-01; 68FM TC-R03-02; 68FM TC-R03-03; and 68FM TC-R03-04; all dated March 18, 2005; to the Cessna Model 680 Citation Airplane Flight Manual (AFM). The TCs describe procedures to recover the cockpit display units in the event that all four cockpit display units go blank during flight. Additionally, these TCs advise the flight crew that, during the use of Taxi, Before Takeoff, Approach, and Before Landing checklists, the briefings (takeoff and approach) should include the possibility of the loss of all cockpit display units and the subsequent transition to standby instruments.
Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.
FAA's Determination and Requirements of This AD
The unsafe condition described previously is likely to exist or develop on other airplanes of the same type design. Therefore, we are issuing this AD to prevent the simultaneous loss of data from all four cockpit display units, and loss of primary navigation instruments, autopilot, flight director, master caution/warning lights, aural warnings, global positioning system position information, and air data and altitude information to non-avionics systems. These losses could reduce the flightcrew's situational awareness, increase flightcrew workload, and consequently reduce the ability to maintain safe flight of the airplane. This AD requires accomplishing the actions specified in the service bulletin described previously, except as discussed under "Difference Between the AD and the Service Bulletin." This AD also requires revising the AFM to include the information in the TCs described previously.
Difference Between the AD and the Service Bulletin
Operators should note that, although the Accomplishment Instructions of the referenced service bulletin describe procedures for submitting a maintenance transaction report recording compliance with the service bulletin, this AD does not require that action. The FAA does not need this information from operators.
Clarification of Actions Beyond What Is Necessary To Prevent the Unsafe Condition
The Cessna service bulletin was being developed for Honeywell Epic Phase 2 certification before the unsafe condition was reported to the FAA. The software upgrade that is necessary for preventing the unsafe condition is included with software upgrades that were developed for the Phase 2 certification. Hardware upgrades that were also developed for the Phase 2 certification are included in the service bulletin. While it is theoretically possible to separate the upgrades and then issue a service bulletin that specifies only the software upgrades necessary to prevent the unsafe conditions, it is impractical to do the service bulletin revision before the effective date of this AD. Therefore, we find it necessary to require accomplishment of all the software upgrades and hardwareupgrades specified in the service bulletin.
FAA's Determination of the Effective Date
An unsafe condition exists that requires the immediate adoption of this AD; therefore, providing notice and opportunity for public comment before the AD is issued is impracticable, and good cause exists to make this AD effective in less than 30 days.
Comments Invited
This AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any relevant written data, views, or arguments regarding this AD. Send your comments to an address listed under ADDRESSES. Include "Docket No. FAA-2005-20916; Directorate Identifier 2005-NM-027-AD" at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD. We will consider all comments received by the closing date and may amend the 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 AD. Using the search function of our docket 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 can review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you can visit http://dms.dot.gov.
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 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 the 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 AD. 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, 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.
Sec. 39.13 [Amended]
2. The FAA amends Sec. 39.13 by adding the following new airworthiness directive (AD):