Airworthiness Directives; Bombardier, Inc. Model DHC-3 Airplanes

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-3 airplanes modified with A. M. Luton's Supplemental Type Certificate (STC) number SA3777NM. This proposed AD would require you to inspect the wiring for the heating blankets on P₃ and P_Y pneumatic lines and the push-to-test function lights to ensure that they are wired to the correct schematic; replace the circuit breaker switch as applicable; and replace the flight manual supplement currently in use with Revision G, dated March 28, 2001 (incorporates Revision I of Sheet I of Drawing 20075, “Electrical System Schematic,” dated October 10, 2000). This proposed AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Canada. We are issuing this proposed AD to detect and correct wiring installed in accordance with an incorrect drawing, which shows the pneumatic heating blankets to the P₃ and P_Y pneumatic lines wired in series with the indicator lights, rather than parallel. This can result in reduced current for the heating blankets and loss of pneumatic line heating, which can lead to loss of engine power or reverse propeller overspeed governing protection and ultimately loss of control of the airplane.

DATES:

We must receive any comments on this proposed AD by July 15, 2004.

ADDRESSES:

Use one of the following to submit comments on this proposed AD:

• By mail: FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 2003-CE-48-AD, 901 Locust, Room 506, Kansas City, Missouri 64106.
• By fax: (816) 329-3771.
• By e-mail: 9-ACE-7-Docket@faa.gov. Comments sent electronically must contain “Docket No. 2003-CE-48-AD” in the subject line. If you send comments electronically as attached electronic files, the files must be formatted in Microsoft Word 97 for Windows or ASCII.

You may get the service information identified in this proposed AD from A. M. Luton, 3025 Eldridge Ave., Bellingham, WA 98225.

You may view the AD docket at FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 2003-CE-48-AD, 901 Locust, Room 506, Kansas City, Missouri 64106. Office hours are 8 a.m. to 4 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:

Richard Simonson, Aerospace Engineer, Special Certification Branch; telephone: 425-917-6507; facsimile: 425-917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

How do I comment on this proposed AD? We invite you to submit any written relevant data, views, or arguments regarding this proposal. Send your comments to an address listed under ADDRESSES. Include “AD Docket No. 2003-CE-48-AD” in the subject line of your comments. If you want us to acknowledge receipt of your mailed comments, send us a self-addressed, stamped postcard with the docket number written on it. We will date-stamp your postcard and mail it back to you.

Are there any specific portions of this proposed AD I should pay attention to? We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. If you contact us through a nonwritten communication and that contact relates to a substantive part of this proposed AD, we will summarize the contact and place the summary in the docket. We will consider all comments received by the closing date and may amend this proposed AD in light of those comments and contacts.

Discussion

What events have caused this proposed AD? Transport Canada, which is the airworthiness authority for Canada, recently notified FAA that an unsafe condition may exist on all Bombardier, Inc. Model DHC-3 airplanes modified with an A. M. Luton Supplemental Type Certificate (STC) number SA3777NM. Transport Canada reports a drawing error on Revisions G and H of Sheet I of the Electrical System Schematic Drawing 20075, which shows the pneumatic heating blankets to the P₃ and P_Y pneumatic lines wired in series with the indicator lights, rather than parallel. This can result in severely reduced electrical energy going to the heating blankets with loss of pneumatic line heating, which can lead to loss of engine power or reverse propeller overspeed governing protection.

What are the consequences if the condition is not corrected? Electrical installation using incorrect wiring configurations could result in the electrical energy being absorbed by the light bulbs with insufficient electrical energy for the heating blankets, which would allow ice to form in these lines due to condensation even though the indication lights show the lines being heated. This could result in loss of engine power or reverse propeller overspeed governing protection and lead to loss of control of the airplane.

Is there service information that applies to this subject? A. M. Luton has issued Service Information Letter SIL-00-10-10, Electrical Systems, dated March 22, 2001.

What are the provisions of this service information? The service letter includes procedures for:

—Replacing the flight manual supplement with Revision G, dated March 28, 2001. This flight manual revision corrects the drawing error on Revisions G and H of Sheet I of the Electrical System Schematic Drawing 20075, by incorporating Revision I of Sheet I of Drawing 20075, “Electrical System Schematic,” dated October 10, 2000;

—Inspecting the push-to-test indicator light for correct wiring; and

—Replacing the circuit breaker switch for the P₃ and P_Y pneumatic heating lines, depending on whether the engine uses one or both heating lines.

What action did Transport Canada take? Transport Canada classified this service bulletin as mandatory and issued Canadian AD Number CF-2002-38, dated August 29, 2002, to ensure the continued airworthiness of these airplanes in Canada.

Did Transport Canada inform the United States per the bilateral airworthiness agreement? These Bombardier, Inc. DHC-3 airplanes are manufactured in Canada 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.

Under this bilateral airworthiness agreement, Transport Canada has kept us informed of the situation described above.

FAA's Determination and Requirements of This Proposed AD

What has FAA decided? We have examined Transport Canada's findings, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States.

Since the unsafe condition described previously is likely to exist or develop on other Bombardier, Inc. DHC-3 airplanes of the same type design modified with A. M. Luton's STC number SA3777NM and are registered in the United States, we are proposing AD action to detect and correct incorrect wiring configuration. This can result in the electrical energy being absorbed by the light bulbs with insufficient electrical energy for the heating blankets, which would allow ice to form in these lines due to condensation even though the indication lights show the lines being heated. This could result in loss of engine power or reverse propeller overspeed governing protection and lead to loss of control of the airplane.

What would this proposed AD require? This proposed AD would require you to incorporate the actions in the previously-referenced service information letter.

How does the revision to 14 CFR part 39 affect this proposed AD? On July 10, 2002, we published a new version of 14 CFR part 39 (67 FR 47997, July 22, 2002), which governs FAA's AD system. This regulation now includes material that relates to altered products, special flight permits, and alternative methods of compliance. This material previously was included in each individual AD. Since this material is included in 14 CFR part 39, we will not include it in future AD actions.

Costs of Compliance

How many airplanes would this proposed AD impact? We estimate that this proposed AD affects 32 airplanes in the U.S. registry.

What would be the cost impact of this proposed AD on owners/operators of the affected airplanes? We have no way of determining the number of airplanes that may need the proposed rewiring or circuit breaker switch replacement. We estimate the following costs to accomplish this proposed inspection:

Regulatory Findings

Would this proposed AD impact various entities? 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.

Would this proposed AD involve a significant rule or regulatory action? For the reasons discussed above, I certify that this proposed 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); 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 summary of the costs to comply with this proposed AD and placed it in the AD Docket. You may get a copy of this summary by sending a request to us at the address listed under ADDRESSES. Include “AD Docket No. 2003-CE-48-AD” in your request.

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 Federal Aviation Administration 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.