# Airworthiness Directives; de Havilland Model DHC-8-100 and DHC-8- 300 Series Airplanes > Briefs, arguments, decisions, and more. URL: https://www.frixlaw.com/law-library/documents/fr%3A94-8054 ## Record - **Collection:** Federal Register - **Document type:** Uncategorized Document - **Published:** April 5, 1994 ## Text DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 93-NM-206-AD] Airworthiness Directives; de Havilland Model DHC-8-100 and DHC-8- 300 Series Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain de Havilland Model DHC-8- 100 and DHC-8-300 series airplanes. This proposal would require a revision to the Airplane Flight Manual (AFM) to advise flight crew members that certain cockpit indications may reveal faulty anti- collision strobe light units, and to provide procedures for subsequent flight crew action. This proposal would also require a modification that eliminates the need for the AFM revision. This proposal is prompted by reports that the function of the proximity switch electronics unit (PSEU) may be adversely effected during operation of the white anti-collision lights. The actions specified by the proposed AD are intended to ensure correct operation of the PSEU and its associated systems. DATES: Comments must be received by May 31, 1994. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 93-NM-206-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule may be obtained from de Havilland, Inc., Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Engine and Propeller Directorate, New York Aircraft Certification Office, 181 South Franklin Avenue, room 202, Valley Stream, New York. FOR FURTHER INFORMATION CONTACT: Michele Maurer, Aerospace Engineer, Systems and Equipment Branch, ANE-173, New York Aircraft Certification Office, FAA, Engine and Propeller Directorate, 181 South Franklin Avenue, room 202, Valley Stream, New York 11581; telephone (516) 791- 6427; fax (516) 791-9024. SUPPLEMENTARY INFORMATION: Comments Invited Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report summarizing each FAA-public contact concerned with the substance of this proposal will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 93-NM-206-AD.'' The postcard will be date stamped and returned to the commenter. Availability of NPRMs Any person may obtain a copy of this NPRM by submitting a request to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 93-NM-206-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion Transport Canada Aviation, which is the airworthiness authority for Canada, recently notified the FAA that an unsafe condition may exist on certain de Havilland Model DHC-8-100 and DHC-8-300 series airplanes. Transport Canada Aviation advises that three field reports indicate that the electrical power supplies of the white anti-collision lights may develop a fault which produces greater than normal electrical emissions. The cause of this fault has been attributed to a capacitor failure in some ``Grimes'' strobe light systems. This electromagnetic interference can adversely affect the operation of the proximity switch electronics unit (PSEU) and its associated systems. The following occurrences have resulted: 1. Flashing of the landing gear green locked down advisory lights during cruise; 2. Fluctuation of the cabin pressurization rate needle during cruise; 3. Retraction and extension of roll and ground spoilers during ground operation; 4. Inoperative nose gear steering subsequent to landing; and 5. Unavailable normal wheel brakes below 35-40 knots. Incorrect operation of the PSEU and its associated systems may interfere with or distract the flight crew in carrying out its regular duties during flight or on the ground, and thus serve to compromise the safe operation of the airplane. De Havilland, Inc., has issued Alert Service Bulletin S.B. A8-33- 33, dated May 31, 1993, that describes flight crew and maintenance procedures to detect faulty power supply units. The alert service bulletin also describes procedures for replacement of any faulty ``Grimes'' unit with a new or serviceable ``Grimes'' unit, or installation of a new ``Whelan'' system (Modification 8/1273). De Havilland, Inc., has also issued Service Bulletin S/B 8-33-19, `Revision A', dated May 31, 1993, that describes procedures for installation of Modification 8/1273, which entails replacing the existing anti-collision strobe light system (consisting of anti- collision strobe lights, brackets, and power supplies) at all three locations with the new, improved ``Whelen'' anti-collision strobe light system. (The ``Whelen'' system includes new dual strobes, new brackets, and new power supplies.) This new system is considered more durable than the currently installed anti-collision strobe light system. The ``Whelan'' system also has a back-up strobe light at each position. Transport Canada Aviation classified these service bulletins as mandatory and issued Canadian Airworthiness Directive CF-93-20, dated August 3, 1993, in order to assure the continued airworthiness of these airplanes in Canada. This airplane model is manufactured in Canada and is type certificated for operation in the United States under the provisions of Sec. 21.29 of the Federal Aviation Regulations and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, Transport Canada Aviation has kept the FAA informed of the situation described above. The FAA has examined the findings of Transport Canada Aviation, 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 an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design registered in the United States, the proposed AD would require revising the Limitations section of the FAA-approved Airplane Flight Manual (AFM) to advise flight crew members that certain cockpit indications during in- flight or ground operations may reveal faulty anti-collision strobe light units, and to provide procedures for subsequent flight crew action. This proposal would also require replacement of faulty ``Grimes'' units with new or serviceable ``Grimes'' units or installation of the new ``Whelan'' system (Modification 8/1273). The proposed AD would also require eventual replacement of the existing anti-collision strobe light system with the ``Whelen'' anti-collision strobe light system (Modification 8/1273) at all three locations. When accomplished, incorporation of this modification would constitute terminating action for the requirements of this proposal. Following incorporation of Modification 8/1273, operators would be permitted to remove the proposed changes to the AFM. The actions would be required to be accomplished in accordance with the service bulletins described previously. Additionally, applicability of the proposed rule would exclude those airplanes on which Modification 8/1273 has been accomplished previously, since airplanes so modified are not subject to the unsafe condition addressed by this proposed AD. The manufacturer has installed Modification 8/1273 on airplanes having serial numbers 215 and subsequent. The FAA estimates that 74 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 16 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $55 per work hour. Required parts for installation of Modification 8/1273 at all three locations would cost approximately $1,397 per airplane. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $168,498, or $2,277 per airplane. The total cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The regulations proposed herein would not have substantial direct effects 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. Therefore, in accordance with Executive Order 12612, it is determined that this proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this 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) 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 is contained in the Rules Docket. A copy of it may be obtained 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, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 14 CFR part 39 of the Federal Aviation Regulations as follows: PART 39--AIRWORTHINESS DIRECTIVES 1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding the following new airworthiness directive: De Havilland, Inc.: Docket 93-NM-206-AD. Applicability: Model DHC-8-102, -103, -302, and -311 series airplanes, serial numbers 003 through 214 inclusive; on which Modification 8/1273 (as described in de Havilland Service Bulletin S/B No. 8-33-19, Revision `A', dated May 31, 1993) has not been accomplished; certificated in any category. Compliance: Required as indicated, unless accomplished previously. To ensure correct operation of the proximity switch electronics unit (PSEU) and its associated systems, accomplish the following: (a) Within 30 days after the effective date of this AD, revise the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to include the following statement. This may be accomplished by inserting a copy of this AD into the AFM. ``The electrical power supplies for the white anti-collision lights may fail and cause the following abnormalities: --Flashing of the landing gear green locked down advisory lights during cruise; --Fluctuation of cabin pressurization rate needle during cruise; and --Retraction and extension of roll and ground spoilers during ground operation. The failure may also result in loss of nose landing gear steering subsequent to landing, and loss of wheel brakes below 35-40 knots. If any of these abnormal indications are observed, select A/COL light switch--RED. Leave the switch in this position for the remainder of the flight.'' (b) If the flight crew reports the occurrence of any of the cockpit indications stated in paragraph (a) of this AD: Prior to the next flight, perform the maintenance procedures to confirm and isolate the faulty power supply unit, in accordance with paragraph III., part B, Accomplishment Instructions of de Havilland Alert Service Bulletin S.B. A8-33-33, dated May 31, 1993. (1) If any power supply unit is determined to be faulty, prior to further flight, replace the unit with a new or serviceable ``Grimes'' unit or a new ``Whelen'' system in accordance with the alert service bulletin. (2) If the specific unit causing the faults cannot be determined, prior to further flight, replace all three units with new or serviceable ``Grimes'' units or a new ``Whelen'' system in accordance with the alert service bulletin. Installation of a new ``Whelen'' system at all three locations constitutes terminating action for the requirements of this AD, and after installation, the AFM revision required by paragraph (a) of this AD may be removed. (c) Within 6 months after the effective date of this AD, install Modification 8/1273 (which entails replacement of the existing anti- collision strobe lights, brackets, and power supplies with the ```Whelen' Anti-Collision Strobe Light System'') at all three locations, in accordance with de Havilland Service Bulletin S/B No. 8-33-19, `Revision A', dated May 31, 1993. Following installation, the AFM revision required by paragraph (a) of this AD may be removed. (d) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, New York Aircraft Certification Office (ACO), ANE-170, FAA, Engine and Propeller Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, New York ACO. Note: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the New York ACO. (e) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished. Issued in Renton, Washington, on March 30, 1994. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 94-8054 Filed 4-4-94; 8:45 am] BILLING CODE 4910-13-U --- Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A94-8054. Public record. Not legal advice.