On September 27, 1993, the FAA issued AD 93-19-05, amendment 39-8703 (58 FR 54940, October 25, 1993), which is applicable to Boeing Model 767 series airplanes, line positions 001 through 402 inclusive. That AD requires (initially) various functional checks of: 1.\tthe leading edge slat shutoff valve, 2. the trailing edge flap drive bypass valve, 3. the leading edge slat long term shutoff control, and 4. the leading edge slat drive mechanical rigging. \n\n\tIn addition, that AD requires installation of terminating modifications for the required functional checks. One of these modifications involves replacing the bypass valve motor of the control valve module for the trailing edge flaps. \n\n\tAD 93-19-05 was prompted by a report of an uncommanded slat extension during cruise, and several instances of an inoperative trailing edge flap bypass valve motor. These instances were attributed to hydraulic fluid in the bypass valve motor. The requirements of that AD are intended to prevent uncommanded deployment of leading edge slats, which could result in structural damage to the wing and consequent degradation of flight control. Additionally, the requirements of that AD are intended to ensure shutdown protection for the trailing edge flap drive in the event of uncommanded or asymmetrical flap motion. \n\n\tSince the issuance of AD 93-19-05, the manufacturer has advised the FAA that three airplanes (those having serial numbers 26847, 27048, and 27049) were delivered on which the replacement of the bypass valve motor in the control valve module for the trailing edge flaps had not been accomplished during production. Those three airplanes were not included in the applicability of AD 93-19-05; however, they are subject to the same unsafe condition addressed by that AD. The FAA has determined that loss of shutdown protection for the trailing edge flap drive due to hydraulic fluid contamination of the bypass valve motor could occur on these three airplanes. \n\n\tThe FAA has reviewed and approved Boeing Service Bulletin 767-27A0094, Revision 5, dated June 9, 1994, which describes (among other actions) procedures to perform a one-time functional check of the bypass valve of the trailing edge flap drive. \n\n\tThe FAA has also reviewed and approved Boeing Service Bulletin 767-27-0138, dated August 17, 1995, which describes procedures for replacement of the control valve module for the trailing edge flaps with an improved module on the three airplanes having serial numbers 26847, 27048, and 27049. The bypass valve motor in the improved module was redesigned to ensure that the motor is hermetically sealed. Accomplishment of this replacement will prevent hydraulic fluid contamination. \n\n\tSince an unsafe condition has been identified that is likely to exist or develop on other Boeing Model 767 series airplanes of the same type design, this AD is being issued to prevent loss of shutdown protection for the trailing edge flap drive, which could result in reduced controllability of the airplane in the event of uncommanded or asymmetrical flap motion. This AD requires a one-time functional check of the trailing edge flap drive bypass valve, and eventual replacement of the control valve module for the trailing edge flaps with an improved module. The actions are required to be accomplished in accordance with the service bulletins described previously. This AD applies only to airplanes having serial numbers 26847, 27048, and 27049. \n\n\t(NOTE: The FAA's normal policy is that when an AD requires a substantive change, such as a change (expansion) in its applicability, the "old" AD is superseded by removing it from the system and a new AD is added. In the case of this AD action, the FAA normally would have proposed superseding AD 93-19-05 to expand its applicability to include the three additional affected airplanes. However, in reconsideration of the entire fleet size that would be affected by a supersedure action, and the consequent workload associated with revising maintenance record entries, the FAA has determined that a less burdensome approach is to issue a separate AD applicable only to the three additional airplanes. This AD does not supersede AD 93-19-05; airplanes listed in the applicability of AD 93-19-05 are required to continue to comply with the requirements of that AD. This AD is a separate AD action, and is applicable only to airplanes having serial numbers 26847, 27048, and 27049.) \n\n\tOperators should note that the manufacturer's recommended compliance time for accomplishment of the functional check is within 400 flight hours after receipt of the service bulletin. While the FAA agrees that 400 flight hours would normally be an appropriate compliance time, this AD specifies a compliance time of 25 days after the effective date of this AD. This compliance time was developed by taking into account the date that the initial service bulletin recommended (September 28, 1989) for accomplishment of the actions and the time that has elapsed since that date. The FAA considered not only the manufacturer's recommendation, but the degree of urgency associated with addressing the subject unsafe condition, as well as the time necessary to perform the functional check (1 work hour). In light of these factors, the FAA finds 25 days to be an appropriate compliance time for initiating the required functional check. \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 Comments Invited \n\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 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. \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 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 befiled 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 Number 96-NM-50-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." List of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\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\n\t1. The authority citation for part 39 continues to read as follows: Authority: 49 USC 106(g), 40113, 44701. § 39.13 - (Amended) \n\t2. Section 39.13 is amended by adding the following new airworthiness directive: