AD 94-22-10 R1 ACTIVE

This amendment revises an existing airworthiness directive (AD), applicable to certain de Havilland Model DHC-8-100 and DHC-8-300 series airplanes, that currently requires 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 and maintenance action. That AD also requires a modification that eliminates the need for the AFM revision. That AD was prompted by reports that the function of the proximity switch electronics unit (PSEU) may be adversely affected during operation of the white anti-collision lights. The actions specified by that AD are intended to ensure correct operation of the PSEU and its associated systems. This amendment revises the applicability of the existing AD to add one model of affected airplanes.

Final rule

94-22-10 R1 DE HAVILLAND: Amendment 39-9122. Docket 94-NM-235-AD. Revises AD 94-22-10, Amendment 39-9060.
Applicability: Model DHC-8-102, -103, -301, and -311 series airplanes, having 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 the applicable time specified in paragraph (a)(1) or (a)(2) of this AD, revise the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to include the following statement. The revision of the AFM 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."

(1) For Model DHC-8-102, -103, and -311 series airplanes: Accomplish the revision of the AFM within 30 days after December 15, 1994 (the effective date of AD 94-22-10, amendment 39-9060),

(2) For Model DHC-8-301 series airplanes: Accomplish the revision of the AFM within 30 days after the effective date of this amendment.

(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, following 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 sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.

(f) The actions shall be done in accordance with de Havilland Alert Service Bulletin S.B. A8-33-33, dated May 31, 1993; and de Havilland Service Bulletin S/B No. 8-33-19, Revision 'A', dated May 31, 1993; as applicable. This incorporation by reference was approved previously by the Director of the Federal Register, in accordance with 5 U.S.C. 552(a) and 1 CFR part 51, as of December 15, 1994 (59 FR 58765, November 15, 1994). Copies may be obtained from de Havilland, Inc., Garratt Boulevard, Downsview, Ontario M3K 1Y5, Canada. Copies may be inspected 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; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

(g) This amendment becomes effective on February 3, 1995.

On October 26, 1994, the FAA issued AD 94-22-10, amendment 39-9060 (59 FR 58765, November 15, 1994), which is applicable to certain de Havilland Model DHC-8-100 and -300 series airplanes. That action requires a revision to the FAA-approved Airplane Flight Manual (AFM) to advise the flight crew that certain cockpit indications may reveal faulty anti-collision strobe light units, and to provide procedures for subsequent flight crew and maintenance action. It also requires the installation of a modification that eliminates the need for the AFM revision.

That action was prompted by reports indicating that the electrical power supplies of the white anti-collision lights may develop a fault that 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. 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. The requirements of AD 94-22-10 are intended to ensure the correct operation of the PSEU and its associated systems.

The AFM revision that is required by AD 94-22-10 is intended to advise the flight crew of the fact that the electrical power supplies for the white anti-collision lights may fail and cause various abnormal indications, such as:

1. flashing of the landing gear green locked down advisory lights during cruise;

2. fluctuation of cabin pressurization rate needle during cruise;

3. retraction and extension of roll and ground spoilers during ground operation;

4. loss of nose landing gear steering subsequent to landing, and

5. loss of wheel brakes below 35-40 knots.

The AFMrevision advises the flight crew that, if any of these abnormal indications are observed, they must select the "A/COL light switch - RED," and leave the switch in this position for the remainder of the flight.

The flight crew and maintenance procedures that are required by AD 94-22-10 are described in de Havilland Alert Service Bulletin S.B. A8-33-33, dated May 31, 1993. These procedures are intended to detect faulty power supply units. The alert service bulletin also describes procedures for replacement of any faulty "Grimes" unit with either a new or serviceable "Grimes" unit or a new "Whelan" system (Modification 8/1273).

The terminating modification that is required by AD 94-22-10 is described in de Havilland Service Bulletin S/B 8-33-19, 'Revision A', dated May 31, 1993. This modification (Modification 8/1273) entails replacing the existing anti-collision strobe light system (consisting of anti-collision strobe lights, brackets, and power supplies) at all three locations with 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.

Subsequent to the issuance of AD 94-22-10, the FAA identified a typographical error in the applicability of the rule: The applicability statement of the AD listed "de Havilland Model DHC-8-302" as a series of airplanes that is subject to the requirements of the rule; however, that model should have been listed as "de Havilland Model DHC-8-301." This airplane model is manufactured in Canada and is type certificated for operation in the United States under the provisions of Section 21.29 of the Federal Aviation Regulations and the applicable bilateral airworthiness agreement. (NOTE: There is no "Model DHC-8-302" that is currently type certificated.)The FAA has determined that the unsafe condition addressed by AD 94-22-10 is likely to exist or develop in Model DHC-8-301 series airplanes. Therefore, AD 94-22-10 must be revised to correctly add these airplanes to its applicability, thereby making them subject to its requirements.

There currently are no Model DHC-8-301 series airplanes on the U.S. Register, however. These airplanes are operated currently by non-U.S. operators under foreign registry; therefore, they are not directly affected by this AD action. However, the FAA considers that this revision to the existing AD is necessary to ensure that the unsafe condition is addressed in the event that any of these airplanes are imported and placed on the U.S. Register in the future.

Should an affected Model DHC-8-301 series airplane be imported and placed on the U.S. Register in the future, it would require approximately 16 work hours to accomplish the required actions, at an average labor charge of $60 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 this AD on an operator of a Model DHC-8-301 series airplane would be $2,357 per airplane.

(The current requirements of AD 94-24-10 affect approximately 74 airplanes of U.S. registry. Accomplishment of the currently required actions take approximately 16 work hours per airplane, at an average labor rate of $60 per airplane. Required parts for installation of Modification 8/1273 at all three locations cost approximately $1,397 per airplane. Based on these figures, the total cost impact of the current requirements of this rule on U.S. operators is estimated to be $174,418, or $2,357 per airplane.)

Since this revision action does not affect any airplane that is currently on the U.S. register, it has no adverse economic impact and imposes no additional burden on any person. Therefore, notice and public procedures hereon are unnecessary and the amendment may be made effective in less than 30 days after publication in the Federal Register.

Comments Invited
Although this action is in the form of a final rule and was not preceded by notice and opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this 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 under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overallregulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the 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 that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 94-NM-235-AD." The postcard will be date stamped and returned to the commenter.

The regulations adopted herein will 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 final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this 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) 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 final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator,the Federal Aviation Administration amends 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89.

39.13 - [Amended]
2. Section 39.13 is amended by removing amendment 39-9060 (59 FR 58765, November 15, 1994), and by adding a new airworthiness directive (AD), amendment 39-9122, to read as follows:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-235-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

The service information referenced in this AD 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; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

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.