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For service information identified in this proposed AD, contact Boeing Commercial Airplanes, PO Box 3707, Seattle, Washington 98124-2207.
You can examine the contents of this AD docket on the Internet at
We invite you to submit any relevant written data, views, or arguments regarding this proposed AD. Send your comments to an address listed under
We will post all comments we receive, without change, to
You can examine the AD docket on the Internet at
We have received reports indicating that, during inspections on two Boeing Model 757-200 airplanes, the ground brackets for the auxiliary power unit (APU) battery were found damaged. Manufacturer analysis found that the bonding surface of the ground brackets had an anodized finish, which reduces electrical conductivity. Further manufacturer investigation of airplanes in production revealed that the method used to clean the ground brackets didn't remove the anodized finish from the bonding surface before the ground wires were installed. This condition, if not corrected, could cause overheating of the ground connections and lead to possible consequent ignition of the adjacent insulating blankets.
The subject ground brackets on certain Boeing Model 757-200PF and -300 airplanes are almost identical to those on the affected Model 757-200 airplanes. Therefore, all of these models may be subject to the same unsafe condition.
We have reviewed Boeing Alert Service Bulletin 757-24A0099 (for Model 757-200 and -200PF series airplanes), and Alert Service Bulletin 757-24A0100 (for Model 757-300 series airplanes); both dated March 25, 2004. The service bulletins describe procedures for inspecting the ground brackets, ground wires, and terminal lugs of the APU battery and the APU start transformer rectifier unit (TRU) ground connections; and corrective and related investigative actions. Corrective actions include cleaning the bonding surfaces of the ground brackets and terminal lugs; and replacing the ground brackets, ground wires, and terminal lugs if necessary. Investigative actions include measuring the electrical resistance between the ground brackets and the terminal lugs and between the ground brackets and the station frame. Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.
We have evaluated all pertinent information and identified an unsafe condition that is likely to exist or develop on other airplanes of this same type design. Therefore, we are proposing this AD, which would require accomplishing the actions specified in the service information described previously.
The Boeing alert service bulletins specify inspecting for damage to certain ground connections, but do not specify the type of inspection to be performed. Paragraph (f) of this proposed AD identifies this inspection as a “general visual inspection,” and Note 1 of this proposed AD defines this inspection.
There are about 251 airplanes of the affected design in the worldwide fleet. This proposed AD would affect about 159 airplanes of U.S. registry.
For about 95 Group 1 and Group 3 airplanes: The proposed inspection and cleaning of the ground connections would take about 2 work hours per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $12,350, or $130 per airplane.
For about 64 Group 2 airplanes: The proposed inspection and cleaning of the ground connection would take about 1 work hour per airplane, at an average labor rate of $65 per work hour. Based on these figures, the estimated cost of the proposed AD for U.S. operators is $4,160, or $65 per airplane.
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,
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. See the
Air transportation, Aircraft, Aviation safety, Safety.
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:
1. The authority citation for part 39 continues to read as follows:
49 U.S.C. 106(g), 40113, 44701.
2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):
(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by April 18, 2005.
(c) This AD applies to Boeing Model 757-200, -200PF, and -300 series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 757-24A0099, and Boeing Alert Service Bulletin 757-24A0100; both dated March 25, 2004.
(d) This AD was prompted by reports indicating that during inspections on two airplanes, the ground brackets for the auxiliary power unit (APU) battery were found damaged. We are issuing this AD to detect and correct a damaged electrical bonding surface of the APU battery and APU start transformer rectifier unit (TRU) ground connections, which could cause overheating of the ground connections and lead to possible consequent ignition of the adjacent insulating blankets.
(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
(f) Within 18 months after the effective date of this AD, perform a general visual inspection for damage of the ground brackets, ground wires, and terminal lugs of the APU battery and APU start transformer rectifier unit (TRU), and do any corrective and related investigative actions; by doing all the actions specified in the Accomplishment Instructions of Boeing Alert Service Bulletin 757-24A0099 (for Model 757-200 and -200PF series airplanes), or Boeing Alert Service Bulletin 757-24A0100 (for Model 757-300 series airplanes); both dated March 25, 2004; as applicable.
For the purposes of this AD, a general visual inspection is “a visual examination of an interior or exterior area, installation or assembly to detect obvious damage, failure or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normal available lighting conditions such as daylight, hangar lighting, flashlight or drop-light and may require removal or opening of access panels or doors. Stands, ladders or platforms may be required to gain proximity to the area being checked.”
(g) The Manager, Seattle Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.