Airworthiness Directives; BAE Systems (Operations) Limited Model BAe 146 and Avro 146-RJ 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 BAE Systems (Operations) Limited Model BAe 146 and Avro 146-RJ airplanes equipped with certain hydraulic accumulators. This proposed AD would require inspecting the hydraulic accumulators to identify certain serial numbers, and replacing any affected accumulator with a new or serviceable accumulator. Operators may delay doing the replacement by doing repetitive inspections of the affected hydraulic accumulators for signs of failure (leaking or cracking), and replacing any failed accumulator with a new or serviceable unit. This proposed AD results from a report that one hydraulic accumulator failed in service, which caused the loss of the yellow hydraulic system when the airplane was configured for landing. We are proposing this AD to prevent damage to the pressure skin, failure of certain hydraulic systems, contamination of the cabin with hydraulic mist, increased workload for the flightcrew associated with the loss of one or more hydraulic circuits, and consequent reduced controllability of the airplane.

DATES:

We must receive comments on this proposed AD by August 18, 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: (202) 493-2251.
• 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 British Aerospace Regional Aircraft American Support, 13850 Mclearen Road, Herndon, Virginia 20171, for service information identified in this proposed AD.

FOR FURTHER INFORMATION CONTACT:

Dan Rodina, Aerospace Engineer, International Branch, ANM-116, Transport Airplane Directorate, FAA, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2125; fax (425) 227-1149.

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-2006-25388; Directorate Identifier 2006-NM-086-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 (800) 647-5227) 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

We have received reports that an unsafe condition may exist on BAE Systems (Operations) Limited Model BAe 146 and Avro 146-RJ airplanes that have hydraulic accumulators, part number (P/N) AIR91666-0, -1, and -2, installed. The European Aviation Safety Agency (EASA) advises that the manufacturer identified two batches of defective hydraulic accumulators after one accumulator burst in service, which caused the loss of the yellow hydraulic system when the airplane was configured for landing. The landing was completed without further incident.

The accumulator was found in the hydraulics bay, detached from its mounting, and shrapnel debris had punctured the pressure skin. Metallurgical examination revealed a pre-existing flaw in the accumulator cylinder casing. A second accumulator with a material flaw in the cylinder casing was identified by non-destructive testing during component overhaul. Further investigation showed that a total of 54 accumulators, P/N AIR91666, were manufactured without the required inspection processes being applied to the cylinder casings. Material flaws within the cylinder could cause the unit to burst in service, resulting in damage to the pressure skin and loss of any services supplied by the system that is connected to the failed accumulator. These services include flaps, lift and roll spoilers, rudder, airbrake, landing gear actuators, nose wheel steering, and wheel brakes. This condition, if not corrected, could result in damage to the pressure skin, failure of certain hydraulic systems, contamination of the cabin with hydraulic mist, increased workload for the flightcrew associated with the loss of one or more hydraulic circuits, and consequent reduced controllability of the airplane.

Relevant Service Information

BAE Systems (Operations) Limited has issued Service Bulletin ISB.29-A046, dated March 14, 2006. The service bulletin describes procedures for inspecting to identify specified serial numbers of hydraulic accumulators with P/N AIR91666-0, -1, and -2 in the yellow and green hydraulic systems and, if applicable, the forward airstairs. If any affected serial number is installed, the service bulletin provides procedures for replacing it before further flight with a new or serviceable unit. A serviceable accumulator is defined as one that is not part of the affected batch, or one on which APPH Service Bulletin AIR91666-29-02, dated March 2006 (described below), has been accomplished. In lieu of replacement, the service bulletin specifies doing the replacement within 135 days provided that operators do repetitive detailed visual inspections for signs of failure (leaks or cracking), and replacing the accumulator with a new or serviceable unit if necessary. The repetitive interval is 48 hours, or before further flight following a report of hydraulic fumes in the cabin air supply, or after a hydraulic fluid low-level warning. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

The EASA mandated Service Bulletin ISB.29-A046, and issued emergency airworthiness directive 2006-0061-E [Corrected], dated March 17, 2006, to ensure the continued airworthiness of these airplanes in the European Union.

The BAE Systems (Operations) Limited service bulletin refers to APPH Service Bulletin AIR91666-29-02, dated March 2006, as an additional source of service information for determining if an accumulator is a serviceable accumulator. The procedures include disassembling the accumulator cylinder and testing it for cracking.

U.S. Type Certification of the Airplane

These airplane models are manufactured in the United Kingdom and are 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 FAA Order 8100.14A, “Interim Procedures for Working with the European Community on Airworthiness Certification and Continued Airworthiness,” dated August 12, 2005, the EASA has kept the FAA informed of the situation described above. We have examined the EASA's findings, evaluated all pertinent information, and determined that we need to issue an AD for products of this type design that are certificated for operation in the United States.

Clarifications of Service Information

Although the BAE Systems (Operations) Limited service bulletin does not specify procedures to follow if more than one affected hydraulic accumulator is found on a single airplane, this proposed AD, in parallel with the EASA airworthiness directive, would allow only one affected hydraulic accumulator to remain in service on the airplane and subject to the proposed repetitive inspections.

The BAE Systems (Operations) Limited service bulletin specifies a detailed visual inspection for signs of leaking. In this proposed AD, we refer to that inspection as a “detailed inspection.” We have included a definition of a detailed inspection in Note 2 of this proposed AD.

Although the BAE Systems (Operations) Limited service bulletin specifies replacing the accumulator within 135 days provided that operators do repetitive detailed visual inspections for signs of failure, this proposed AD would require this replacement within 75 days after the effective date of this proposed AD. This compliance time parallels the compliance time for the replacement that is specified in EASA emergency airworthiness directive 2006-0061-E [Corrected].

Changes to 14 CFR Part 39/Effect on the AD Relating to Special Flight Permits

On July 10, 2002, the FAA issued a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs the FAA's airworthiness directives system. The regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance (AMOCs). This material is included in part 39, except that the office authorized to approve AMOCs is identified in each individual AD. However, as amended, part 39 provides for the FAA to add special requirements for operating an airplane to a repair facility to do the work required by an airworthiness directive. For the purposes of this proposed AD, we have determined that such a special flight permit would be limited before all affected hydraulic actuators are replaced on the airplane. A special flight permit is allowed only if the airplane has not flown more than 5 flight cycles since the last inspection done in accordance with paragraph (g)(2) or (g)(3) of this proposed AD, as applicable; and if the flight can be accomplished in one flight cycle with the airplane unpressurized.

Costs of Compliance

This proposed AD would affect about 42 airplanes of U.S. registry. The proposed inspection to determine the serial number would take about 1 work hour per airplane, at an average labor rate of $80 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $3,360, or $80 per airplane.

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.