01-5169. Airworthiness Directives; Pilatus Aircraft LTD Models PC-12 and PC-12/45 Airplanes

AGENCY:

Federal Aviation Administration, DOT.

ACTION:

Notice of proposed rulemaking (NPRM).

SUMMARY:

This document proposes to supersede Airworthiness Directive (AD) 99-17-08, which currently requires modifying the generator 2 excitation by removing certain diodes and installing a new 5-amp circuit breaker and suppression filter found on certain Pilatus Aircraft Ltd. (Pilatus) Models PC-12 and PC-12/45 airplanes. The Federal Aviation Administration has determined that the A250 voltage spike suppression filter in the modification kit can cause the circuit breaker 235 to trip because of overload. In extreme circumstances, this can lead to overheating of wiring. The proposed AD would require modifying the generator 2 excitation by removing certain diodes, installing a new 5-amp circuit breaker and new suppression filter requirement in accordance with revised procedures. The proposed AD is the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland. The actions specified by the proposed AD are intended to prevent damage to electrical components if generator 2 is not switched off before engine shutdown and it overheats. This could result in loss of electrical power to certain critical airplane components.

DATES:

The FAA must receive any comments on this proposed rule by April 12, 2001.

ADDRESSES:

Send three copies of comments to FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 99-CE-82-AD, 901 Locust, Room 506, Kansas City, Missouri 64106. Comments may be inspected at this location between 8 a.m. and 4 p.m., Monday through Friday, except holidays.

You may get service information that applies to the proposed AD from Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, Switzerland; telephone: [phone]; facsimile: [phone]. You may also read this information at the Rules Docket at the address above.

FOR FURTHER INFORMATION CONTACT:

Roman T. Gabrys, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106; telephone: [phone]; facsimile: [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

How do I comment on this proposed AD? We invite your comments on the proposed rule. You may send whatever written data, views, or arguments you choose. You need to include the rule's docket number and send your comments in triplicate to the address mentioned under the caption ADDRESSES. We will consider all comments received by the closing date mentioned above, before acting on the proposed rule. We may change the proposals contained in this notice because of the comments received.

Are there any specific portions of the proposed AD I should pay attention to? The FAA specifically invites comments on the overall regulatory, economic, environmental, and energy aspects of the proposed rule that might call for a need to change the proposed rule. You may read all comments we receive. We will file a report in the Rules Docket that summarizes each FAA contact with the public that concerns the substantive parts of this proposal.

The FAA is reexamining the writing style we currently use in regulatory documents, in response to the Presidential memorandum of June 1, 1998. That memorandum requires federal agencies to communicate more clearly with the public. We are interested in your comments on the ease of understanding this document, and any other suggestions you might have to improve the clarity of FAA communications that affect you. You can get more information about the Presidential memorandum and the plain language initiative at http://www.faa.gov/​language/​.

How can I be sure FAA receives my comment? If you want us to acknowledge the receipt of your comments, you must include a self-addressed, stamped postcard. On the postcard, write “Comments to Docket No. 99-CE-82-AD.” We will date stamp and mail the postcard back to you.

Discussion

Has FAA taken any action to this point? The FAA issued AD 99-17-08, Amendment 39-11256 (64 FR 45149, August 19, 1999), against Pilatus models PC-12 and PC-12/45 airplanes, to prevent damage to electrical components if generator 2 is not switched off before engine shutdown and it overheats. This could result in loss of electrical power to certain critical airplane components of Pilatus Models PC-12 and PC-12/45 airplanes.

AD 99-17-08 requires that you do the following on the affected airplanes:

—modify the generator 2 excitation by removing certain diodes; and

—install a new 5-amp circuit breaker and suppression filter.

AD 99-17-08 was the result of mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Switzerland.

What has happened since AD 99-17-08 to begin this action? The Federal Office for Civil Aviation (FOCA), which is the airworthiness authority for Switzerland, recently notified FAA of the need to change AD 99-17-08. The FOCA reports that after installation of Pilatus Service Bulletin SB 21-012 and turning on electrical power on one of the affected airplanes, the circuit breaker CB 235 tripped.

Investigation revealed that the suppression filter (A250) (part number 524.52.12.358) was shorted. The suppression diode, installed in the filter was shorted and the wrong type. The manufacturer's A250 voltage spike suppression filter is inadequate and must be replaced with a new A250 voltage spike suppression filter.

Is there service information that applies to this subject? Pilatus issued:

—Service Bulletin No 24-012, dated February 19, 1999; and

—Service Bulletin No 24-014, dated October 27, 1999.

What are the provisions of these service bulletins? These service bulletins include procedures for:

—modifying the generator 2 excitation by removing certain diodes and installing a new 5-amp circuit breaker and suppression filter;

—removing the A250 voltage spike suppression filter; and

—installing the new A250 voltage spike suppression filter.

What action did the FOCA take? The FOCA classified both service bulletins as mandatory and issued Swiss AD HB 99-143, dated February 19, 1999, and AD HB 99-542, dated October 29, 1999, to assure the continued airworthiness of these airplanes in Switzerland.

Was this in accordance with the bilateral airworthiness agreement? This airplane model is manufactured in Switzerland and is 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.

Complying with this bilateral airworthiness agreement, the FOCA has kept FAA informed of the situation described above.

The FAA's Determination and an Explanation of the Provisions of the Proposed AD

What has FAA decided? The FAA has examined the findings of the FOCA; reviewed all available information, including the service information referenced above; and determined that:

—the unsafe condition referenced in this document exists or could develop on other Pilatus Models PC-12 and PC-12/45 airplanes of the same type design that are equipped with one of the previously referenced stabilizer trim actuators;

—the actions specified in the previously-referenced service information should be done on the affected airplanes; and

—AD action should be taken to correct this unsafe condition.

What would the proposed AD require? This proposed AD would supersede AD 99-17-08 with a new AD that would require you to incorporate the actions in the previously referenced service bulletins.

Cost Impact

How many airplanes would the proposed AD impact? We estimate that the proposed AD affects 69 airplanes in the U.S. registry.

What would be the cost impact of the proposed AD on owners/operators of the affected airplanes? We estimate the following costs to do the proposed modification of the generator 2 excitation:

Labor cost	Parts cost	Total cost per airplane	Total cost on U.S. airplane operators
8 workhours × $60 per hour = $480	Parts will be provided at no cost to the owners/operators of the affected aircraft	$480	$33,120

If the modification of the generator 2 excitation has been done with the manufacturer's modification kit, then we estimate the following costs to remove the A250 voltage spike suppression filter and replace it with the new A250 voltage spike suppression filter:

Labor Cost	Parts cost	Total cost per airplane	Total cost on U.S. airplane operators
3 workhours × $60. per hour = $180	Parts will be provided at no cost to the owners/operators of the affected aircraft	$180	$12,420

Regulatory Impact

Would this proposed AD impact various entities? The regulations proposed 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. We have determined that this proposed rule would not have federalism implications under Executive Order 13132.

Would this proposed AD involve a significant rule or regulatory action? For the reasons discussed above, I certify that this proposed action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, 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. A copy of the draft regulatory evaluation prepared for this action has been placed in the Rules Docket. You may request copy by contacting the Rules Docket at the location provided under the caption ADDRESSES.

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 part 39 of the Federal Aviation Regulations (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. FAA amends § 39.13 by removing airworthiness directive (AD) 99-17-08, Amendment 39-11256 (64 FR 45149, August 19, 1999), and by adding a new AD to read as follows:

Pilatus Aircraft Ltd.: Docket No. 99-CE-82-AD; Supersedes AD 99-17-08, Amendment 39-11256.

(a) What airplanes are affected by this AD? This AD affects Models PC-12 and PC-12/45 airplanes, serial numbers 101 through 289, that are certificated in any category.

(b) Who must comply with this AD? Anyone who wishes to operate any of the above airplanes must comply with this AD.

(c) What problem does this AD address? The actions specified by this AD are intended to prevent damage to electrical components if generator 2 is not switched off before engine shutdown and it overheats. This could result in loss of electrical power to certain critical airplane components.

(d) What actions must I accomplish to address this problem? To address this problem, unless already done, you must do the following:

Action	Compliance time	Procedures
(1) Modify the generator 2 excitation with the modification kit, part number 500.50.12.192, replacing the A250 voltage spike suppression filter, part number 524.52.12.358, with a new A250 voltage spike suppression filter, part number 524.52.12.502	Within the next 100 hours time-in-service (TIS) after the effective date of this AD	Do this action following the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus Service Bulletin No. 24-012, dated February 19, 1999, and Service Bulletin No. 24-014, dated October 27, 1999.
(2) If the modification kit, part number 500.50.12.192, is already installed using the A250 voltage spike suppression filter, part number 524.52.12.358, only replace this voltage spike suppression filter with a new A250 voltage spike suppression filter, part number 524.52.12.502	Within the next 100 hours TIS after the effective date of this AD	Do this action following the ACCOMPLISHMENT INSTRUCTIONS section of Pilatus Service Bulletin No. 24-014, dated October 27, 1999.
(3) Do not install any A250 voltage spike suppression filter, part number 524.52.12.358, or FAA-approved equivalent part number	As of the effective date of this AD	Not Applicable.

(e) Can I comply with this AD in any other way? You may use an alternative method of compliance or adjust the compliance time if:

(1) Your alternative method of compliance provides an equivalent level of safety; and

(2) The Manager, Small Airplane Directorate, approves your alternative. Send your request through an FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Small Airplane Directorate.

Note 1:

This AD applies to each airplane identified in paragraph (a) of this AD, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if you have not eliminated the unsafe condition, specific actions you propose to address it.

(f) Where can I get information about any already-approved alternative methods of compliance? Contact Roman T. Gabrys, Aerospace Engineer, FAA, Small Airplane Directorate, 901 Locust, Room 301, Kansas City, Missouri 64106; telephone: [phone]; facsimile: [phone].

(g) What if I need to fly the airplane to another location to comply with this AD? The FAA can issue a special flight permit under sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate your airplane to a location where you can accomplish the requirements of this AD.

(h) How do I get copies of the documents referenced in this AD? You may get copies of the documents referenced in this AD from Pilatus Aircraft Ltd., Customer Liaison Manager, CH-6371 Stans, Switzerland; telephone: [phone]; facsimile: [phone]. You may read these documents at FAA, Central Region, Office of the Regional Counsel, 901 Locust, Room 506, Kansas City, Missouri 64106.

Note 2:

The subject of this AD is addressed in these Swiss AD's:

—HB 99-143, dated February 19, 1999; and

—HB 99-542, dated October 29, 1999.

Issued in Kansas City, Missouri, on February 26, 2001.

Michael Gallagher,

Manager, Small Airplane Directorate, Aircraft Certfication Service.