AD 99-08-07 ACTIVE

This amendment supersedes an existing priority letter airworthiness directive (AD) 98-17-14, applicable to MDHS Model 369E, 369FF, 500N, and 600N helicopters, that currently requires, within the next 14 calendar days, inspecting each relay receptacle contact socket for correct size of the contact socket holes and replacing incorrectly-sized contact sockets with airworthy contact sockets. This amendment requires the same inspections and replacements as the existing priority letter AD, but changes the serial numbers affected for the MDHS Model 500N and 600N helicopters and changes a part number that was incorrectly referenced in the existing AD. This amendment is prompted by three incidences in which a MDHS Model 600 helicopter's Engine Control Unit (ECU) Fail light illuminated, even though the ECU continued to automatically control the engine. The cause of the ECU malfunction indication was determined to be contact sockets that did not properly fit the corresponding pins ofthe affected relay. Improperly sized contact sockets could create multiple unsafe conditions. These conditions, if not corrected, could result in the loss of various engine control or warning systems including the undetected loss of the auto-reignition function after an engine flameout, failure of an engine to reignite, and a subsequent forced landing and the inability to immediately detect an engine-out condition or to properly govern main rotor speed following loss of the Full Authority Digital Engine Control (FADEC), and subsequent loss of control of the helicopter.

Final rule; request for comments

99-08-07 MCDONNELL DOUGLAS HELICOPTER SYSTEMS: Amendment 39-11113. Docket No. 99-SW-11-AD. Supersedes Priority Letter AD 98-17-14, Docket No. 98-SW-32-AD. \n\n\tApplicability: Model 369E (serial numbers (S/N) 384E through 0539E); Model 369FF (S/N 076FF through 0128FF); Model 500N (serial numbers up to and including LN085); and Model 600N (serial numbers RN002 through RN039) helicopters, certificated in any category. \n\n\tNOTE 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters 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 the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. \n\n\tCompliance: Required within the next 14 calendar days, unless accomplished previously. To prevent undetected loss of engine control or warning systems, accomplish the following: \n\n\t(a)\tAccess relays K1, K2, K3, K5, K104, and K200 (relays, part number (P/N) HS4240). \n\n\t(b)\tRemove each relay specified in paragraph (a) from its relay receptacle (receptacle), P/N HS4256-1. \n\n\t(c)\tUsing a No. 60 drill bit or a 0.040-in. diameter wire as a gauge, attempt to insert the gauge into every contact socket (socket) of each relay. Ensure the gauge is inserted perpendicular to the face of the receptacle, to prevent damage to the receptacle and the socket (Figure 1). If the gauge can be inserted into a socket, it is unairworthy and must be replaced with an airworthy socket, P/N 019-0075-002. \n\n\n\n\nFigure 1.Contact Socket Inspection \nAD 99-08-07 \n\n\t(d)\tAny replacement relay, P/N HS4240, must be inspected prior to further flight, in accordance with paragraph (c) of this AD. \n\n\tNOTE 2: Boeing MDHS Service Bulletin, SB369E-090, SB369F-077, SB500N-017, SB600N-014, dated July 6, 1998, pertains to the subject of this AD. \n\n\t(e)\tAn 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, Los Angeles Aircraft Certification Office, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Los Angeles Aircraft Certification Office. \n\n\tNOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles Aircraft Certification Office. \n\n\t(f)\tSpecial 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 helicopter to a location where the requirements of this AD can be accomplished. \n\n\t(g)\tThis amendment becomes effective on April 21, 1999.

On August 14, 1998, the FAA issued Priority Letter AD 98-17-14, applicable to MDHS Model 369E, 369FF, 500N and 600N helicopters, that requires, within the next 14 calendar days, inspecting each relay receptacle, part number (P/N) HS4256-1, contact sockets for correct size of the contact socket holes, and replacing incorrectly-sized contact sockets with airworthy contact sockets, P/N 019-0075-002. That action was prompted by an incident in which a MDHS Model 600 helicopter's ECU Fail light illuminated, even though the ECU continued to automatically control the engine. The helicopter manufacturer reported two additional similar incidents on other MDHS Model 600N helicopters. The cause of the ECU malfunction indication was determined to be contact sockets that did not properly fit the corresponding pins of the affected relay. That condition, if not corrected, could result in the loss of the Battery Hi Temp. relay and the Auto-Re-Ignition Igniter relayon MDHS Model 369E, 369FF, and 500N helicopters. The loss of these engine control or warning systems could result in multiple unsafe conditions, including the undetected loss of the auto-reignition function after an engine flameout, failure of an engine to reignite, and a subsequent forced landing. Also, that condition, if not corrected, could result in the undetected loss of the Battery Hi Temp. relay and the FADEC-related relays (which includes the ECU Fail relay, the Engine-Out relay, the Manual Mode relay, the FADEC Start relay, and the Voice Warning Unit) on MDHS Model 600N helicopters. The undetected loss of these engine control or warning systems could result in multiple unsafe conditions, including the inability to immediately detect an engine-out condition or to properly govern main rotor speed following loss of the FADEC, and subsequent loss of control of the helicopter. \n\n\tSince the issuance of that AD, the FAA has determined that not all of the previously affected MDHSModel 600N helicopters have the unsafe condition; the prefix "RN" for the serial number for the MDHS Model 500N helicopters is incorrect; and the part number for the relay receptacle was incorrectly stated in Figure 1. \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other MDHS Model 369E, 369FF, 500N and 600N helicopters of the same type design, this AD supersedes Priority Letter AD 98-17-14 to require, within the next 14 calendar days, inspecting each affected relay receptacle contact socket for correct size of the contact socket holes, and replacing incorrectly-sized sockets with airworthy contact sockets. The short compliance time involved is required because the previously described critical unsafe condition can adversely affect the controllability of the helicopter. Therefore, inspecting each suspect relay receptacle contact socket for correct size of the contact socket holes and replacing incorrectly-sized sockets with airworthy contactsockets is required within the next 14 calendar days, and this AD must be issued immediately. \n\n\tSince a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days. \n\n\tThe FAA estimates that 156 helicopters of U.S. registry will be affected by this AD, that it will take approximately 4 work hours per helicopter to inspect and replace all contact sockets, and that the average labor rate is $60 per work hour. Required parts will cost approximately $864 per helicopter. Based on these figures, the total cost impact of the AD on U.S. operators is estimated to be $172,224 assuming one inspection per helicopter and replacement of all contact sockets on all the helicopters in the U.S. fleet. \n\nComments Invited \n\tAlthough this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an 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 should 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. \n\n\tComments are specifically invited on the overall regulatory, 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 afterthe 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. \n\n\tCommenters 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 No. 99-SW-11-AD. The postcard will be date stamped and returned to the commenter. \n\n\tThe 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. \n\n\tThe FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES." \n\nList of Subjects in 14 CFR Part 39 \n\tAir transportation, Aircraft, Aviation safety, Safety. \n\nAdoption of the Amendment \n\tAccordingly, 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: \n\nPART 39 - AIRWORTHINESS DIRECTIVES \n\t1. The authority citation for part 39 continues to read as follows: \n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended) \n\t2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Office of the Regional\nCounsel, Southwest Region, Attention: Rules Docket No. 99-SW-11-AD, 2601 Meacham Blvd., Room 663, Fort Worth,\nTexas 76137.

Bruce Conze, Aerospace Engineer, FAA, Los Angeles Aircraft Certification Office, 3960 Paramount Blvd., Lakewood, California 90712, telephone (562) 627-5261, fax (562) 627-5210.