E6-16891. Airworthiness Directives; McDonnell Douglas Model 717-200 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 McDonnell Douglas Model 717-200 airplanes. This proposed AD would require inspecting the power conversion distribution unit (PCDU) to determine its part number, and modifying certain PCDUs. This proposed AD is prompted by reports of failed PCDUs, the loss of an electrical bus, and the presence of a strong electrical burning odor in the flight deck and forward cabin. We are proposing this AD to prevent the loss of an electrical bus due to a PCDU failure, which could result in an abnormally long time for all flight deck displays to reconfigure, and consequent emergency landing.

DATES:

We must receive comments on this proposed AD by November 27, 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.
• By fax: [phone].
• 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.

For service information identified in this proposed AD, contact Boeing Commercial Airplanes, Long Beach Division, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Data and Service Management, Dept. C1-L5A (D800-0024).

You can examine the contents of this AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., room PL-401, on the plaza level of the Nassif Building, Washington, DC. This docket number is FAA-2006-26043; the directorate identifier for this docket is 2005-NM-010-AD.

FOR FURTHER INFORMATION CONTACT:

Thomas Phan, Aerospace Engineer, Systems and Equipment Branch, ANM-130L, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Boulevard, Lakewood, California 90712-4137; telephone [phone]; fax [phone].

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 under ADDRESSES. Include “Docket No. FAA-2006-26043; Directorate Identifier 2005-NM-010-AD” in the subject line 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 submitted 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 can review 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.

Examining the Docket

You can 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 [phone]) 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 DMS receives them.

Discussion

We have received reports of failed power conversion distribution units (PCDUs). Such failures resulted, by design, in the loss of an electrical bus (both AC and DC power). Following the loss of the electrical bus, the flight deck displays took an abnormally long time to reconfigure, and a strong electrical burning odor was noted in the flight deck and forward cabin. Investigation revealed a short in the power supply of the PCDU's generator control unit. The strong electrical burning odor in the cabin has been attributed to a failed PCDU on which a short condition can result in overheating of the power supply T1 transformer. Further, service history has shown that an intermittent loss of engine N2 speed signal to the PCDU can result in a bus tie lockout condition and automatic activation of the emergency power. The loss of an electrical bus due to a failed PCDU could result in an abnormally long time for all flight deck displays to reconfigure, and consequent emergency landing.

Relevant Service Information

We have reviewed Boeing Alert Service Bulletin 717-24A0028, Revision 1, dated December 20, 2005. The service bulletin describes procedures for modifying PCDUs having part number 762904E. The modification involves modifying the printed wiring board (PWB) assembly A4 and installing new PCDU firmware.

The Boeing service bulletin refers to Hamilton Sundstrand Service Bulletin 40EGS22P-24-10, dated August 4, 2004, as an additional source of service information for the modification.

Hamilton Sundstrand Service Bulletin 40EGS22P-24-10 specifies the concurrent accomplishment of the actions specified in the Hamilton Sundstrand service bulletins listed in the following table:

Concurrent Service Bulletins

Actions	Hamilton Sundstrand Service Bulletin	Revision level	Date
Reworking the transformer rectifier unit assembly (TRU)	40EGS22P-24-3	Original	June 30, 2000.
Reworking the W3 wiring harness assembly to install direct lead wires to the TRU.
Adding a ground wire to the TRU transformer.
Adding an insulated spacer to the PCDU top cover.
Installing new PCDU 186 firmware	40EGS22P-24-4	Original	April 26, 2001.
		1	January 2, 2002.
Installing new PCDU 186 firmware	40EGS22P-24-6	Original	July 25, 2002.
Modifying the top cover of the PCDU	40EGS22P-24-7	Original	September 3, 2003.
Modifying PWB assemblies A4 and A5	40EGS22P-24-8	Original	September 4, 2003.
Checking and applying torque seal to fasteners on the TRU assembly and to PCDU internal fasteners, if necessary.
Modifying PWB assembly A4	40EGS22P-24-9	Original	November 19, 2003.

Accomplishing the actions specified in the service information is intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

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 identifying the part number of the PCDU and accomplishing the applicable actions specified in the service information described previously.

Costs of Compliance

There are about 137 airplanes of the affected design in the worldwide fleet and 108 U.S.-registered airplanes. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.

Estimated Costs for Primary Actions

Boeing Service Bulletin	Work hours	Labor rate per hour	Parts cost	Cost per airplane
Part number identification	1	$80	$0	$80
Modification (717-24A0028)	12	80	0	960

Estimated Costs for Concurrent Actions

Hamilton Sundstrand Service Bulletin	Work hours	Labor rate per hour	Parts cost	Cost per airplane
40EGS22P-24-3	6	$80	$154, per airplane	$634
40EGS22P-24-4	3	80	0	240
40EGS22P-24-6	3	80	0	240
40EGS22P-24-7	1 per PCDU	80	10 per PCDU, maximum 3 PCDUs per airplane	1 110
40EGS22P-24-8	10	80	0	800
40EGS22P-24-9	10	80	0	800
1 Maximum.

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. 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.

§ 39.13

[Amended]

2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD):

McDonnell Douglas: Docket No. FAA-2006-26043; Directorate Identifier 2005-NM-010-AD.

Comments Due Date

(a) The Federal Aviation Administration (FAA) must receive comments on this AD action by November 27, 2006.

Affected ADs

(b) None.

Applicability

(c) This AD applies to all McDonnell Douglas Model 717-200 airplanes, certificated in any category.

Unsafe Condition

(d) This AD was prompted by reports of failed power conversion distribution units (PCDUs), the loss of an electrical bus, and the presence of a strong electrical burning odor in the flight deck and forward cabin. We are issuing this AD to prevent the loss of an electrical bus due to a PCDU failure, which could result in an abnormally long time for all flight deck displays to reconfigure, and consequent emergency landing.

Compliance

(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.

Identification of PCDU Part Number

(f) Within 20 months after the effective date of this AD, inspect the PCDU to determine its part number. A review of airplane maintenance records is acceptable in lieu of this inspection if the part number can be conclusively determined from that review.

(1) If the part number is 762904E, do the actions specified in paragraphs (g) and (h) of this AD.

(2) If the part number is not 762904E, no further work is required by this AD.

Modification

(g) Within 20 months after the effective date of this AD, modify the PCDU in accordance with Boeing Alert Service Bulletin 717-24A0028, Revision 1, dated December 20, 2005. A modification done before the effective date of this AD in accordance with Boeing Alert Service Bulletin 717-24A0028, dated November 24, 2004, is acceptable for compliance with the requirements of this paragraph.

Note 1:

Boeing Alert Service Bulletin 717-24A0028 refers to Hamilton Sundstrand Service Bulletin 40EGS22P-24-10, Revision 1, dated May 11, 2005, as an additional source of service information for the modification.

Concurrent Requirements

(h) Before or concurrently with the modification required by paragraph (g) of this AD, do the applicable actions specified in Table 1 of this AD.

Table 1.—Concurrent Service Bulletins

Do the following—	In accordance with Hamilton Sundstrand Service Bulletin—
Rework the transformer rectifier unit assembly (TRU)	40EGS22P-24-3, dated June 30, 2000.
Rework the W3 wiring harness assembly to install direct lead wires to the TRU.
Add a ground wire to the TRU transformer.
Add an insulated spacer to the PCDU top cover.
Install new PCDU 186 firmware	40EGS22P-24-4, Revision 1, dated January 2, 2002.
Install new PCDU 186 firmware	40EGS22P-24-6, dated July 25, 2002.
Modify the top cover of the PCDU	40EGS22P-24-7, dated September 3, 2003.
Modify printed wiring board (PWB) assemblies A4 and A5	40EGS22P-24-8, dated September 4, 2003.
Check and apply torque seal to fasteners on the TRU assembly and to PCDU internal fasteners, as applicable.
Modify the PWB assembly A4	40EGS22P-24-9, dated November 19, 2003.

Credit for Accomplishment of Earlier Service Bulletin

(i) Installation of new PCDU 186 firmware before the effective date of this AD in accordance with Hamilton Sundstrand Service Bulletin 40EGS22P-24-4, dated April 26, 2001, is acceptable for compliance with the corresponding requirements of paragraph (h) of this AD.

Alternative Methods of Compliance (AMOCs)

(j) The Manager, Los Angeles Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

Issued in Renton, Washington, on October 3, 2006.

Kalene C. Yanamura,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.