AD 96-01-51

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) T96-01-51 that was sent previously to all known U.S. owners and operators of certain Boeing Model 747-100 and -200 airplanes by individual telegrams. This AD requires repetitive inspections of the latch safety pins of the main deck side cargo door to ensure that the door is securely latched and locked; it also requires deactivation of certain panel lights and installation of a placard to indicate such deactivation. This amendment is prompted by a report of a malfunction of the safety interlock system of the main deck side cargo door on one airplane. The actions specified by this AD are intended to prevent such malfunctions, which could result in the opening of the main deck side cargo door while the airplane is in flight, and subsequent rapid decompression of the airplane.

Final rule; request for comments

96-01-51 BOEING: Amendment 39-9492. Docket 96-NM-01-AD. \n\n\tAPPLICABILITY: Model 747-100 series airplanes having serial numbers 19637, 19638, 19642, 19647, 19648, 19657, 19725, 20320, and 20347, that have been modified in accordance with Supplemental Type Certificate (STC) SA2322SO; and Model 747-200 series airplane having serial number 20010 that has been modified in accordance with STC SA4227NM-D; certificated in any category. \n\n\tNOTE 1: This AD applies to each airplane 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 airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must use the authority provided in paragraph (d) of this AD to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition; or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no case does the presence of any modification, alteration, or repair remove any airplane from the applicability of this AD. \n\n\tCOMPLIANCE: Required as indicated, unless accomplished previously. \n\n\tTo prevent malfunction of the safety interlock system of the main deck cargo door and subsequent rapid decompression of the airplane due to in-flight opening of the main deck side cargo door, accomplish the following: \n\n\t(a)\tNotwithstanding the requirements of paragraph E. of AD 90-09-06, amendment 39-6581, within 3 days after the effective date of this AD, deactivate the "LATCHES UNLOCKED" light at the door operating panel and the "DOOR UNLOCKED" light at the flight engineer (F/E) panel; and fabricate and install placards; in accordance with a methodapproved by the Manager, Atlanta Aircraft Certification Office (ACO), FAA, Small Airplane Directorate. \n\n\t(b)\tWithin 3 days after the effective date of this AD, accomplish the requirements of paragraphs (b)(1), (b)(2), (b)(3), (b)(4), (b)(5), AND (b)(6) of this AD. Repeat these procedures thereafter prior to each flight. These procedures must be performed by properly trained and qualified maintenance personnel. \n\n\t\t(1)\tClose the main deck side cargo door in accordance with normal \noperations procedures.\n \n\t\t(2)\tUnscrew, lift, and secure the door lower access panels in the "UP" \nposition. \n\n\t\t(3)\tPerform a visual inspection of all 12 latch and lock arms to ensure that they are overcenter in the "LOCKED" position and that all alignment marks line-up correctly. \n\n\t\t(4)\tPerform a detailed visual inspection to ensure that the ten photo scanner alignment holes in latches 2 through 11 have no obstructions. \n\n\t\t\t(i)\tCounting forward to aft, install pins in photo scanner \t\t\t\talignment holes in latch assemblies 2 through 11. The safety pins must engage the lock arm and latch arm lever, and go completely through the latch assembly. \n\n\t\t\t(ii)\tAll latch safety pins must be fastened together with a safety \ncable, and the safety cable must be attached to the main deck door sill protector. \n\n\t\t\t(iii)\tLower and secure the lower access panels in place. \n\n\t\t\t(iv)\tOpen circuit breaker HC5, located on P-10, main power \n\t\t\t\tcenter-left. \n\n\t\t(5)\tTo close the pressure vent door on the main deck side cargo door, \naccomplish paragraphs (b)(5)(i), (b)(5)(ii), (b)(5)(iii), AND (b)(5)(iv) of this AD: \n\n\t\t\t(i)\tRemove pressure vent door cover; \n\t\t\t(ii)\tManually retract the two solenoid valves to allow pressure \t\t\t\tvent door closure; \n\t\t\t(iii)\tClose pressure vent door; and \n\t\t\t(iv)\tReplace vent door cover. \n\n\t\t(6)\tAll safety pins must be removed before opening or operating cargo \n\t\t\tdoor. \n\n\t(c)\tAccomplishment of a modification in accordance with a method approved by the Manager, Atlanta ACO, FAA, Small Airplane Directorate, constitutes terminating action for the requirements of this AD. \n\n\t(d)\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, Atlanta ACO, FAA, Small Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Atlanta ACO. \n\n\tNOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Atlanta ACO. \n\n\t(e)\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 airplane to a location where the requirements of this AD can be accomplished. \n\n\t(f)\tThis amendment becomes effective on January 29, 1996, to all persons except those persons to whom it was made immediately effective by telegraphic AD T96-01-51, issued on January 3, 1996, which contained the requirements of this amendment.

The FAA has recently received a report that the flightcrew on a Boeing Model 747-100 series airplane noted an abnormal cabin altitude rate of climb. Although the pressurization vent door light was not illuminated (which signified to the flightcrew that the door was closed and locked), the flightcrew was unable to pressurize the airplane. The flightcrew also noted that the main deck side cargo door "DOOR UNLOCKED" light illuminated shortly after takeoff. Investigation revealed that 11 of the 12 latches on the main deck side cargo door were unlatched and unlocked. However, the pressurization vent door was closed and locked; this would signify that a malfunction of the safety interlock system had occurred. \n\n\tA properly functioning safety interlock system electro-mechanically prevents the pressurization vent door from closing until all of the latches are in the fully latched and locked position. If the pressurization vent door is not closed, the airplane cannot be pressurized. \n\n\tAlthough the original cause of the failure to properly latch the door may be attributable to human error, the purpose of the interlock system is to ensure that such errors are detected so that the airplane cannot be pressurized unless the main deck side cargo door is properly latched and locked. Malfunction of the safety interlock system of the main deck side cargo door, if not corrected, could result in an in-flight opening of the main deck side cargo door, and subsequent rapid decompression of the airplane. \n\n\tThe airplane in the reported incident was a Model 747-100 series airplane that had been modified in accordance with Supplemental Type Certificate (STC) SA2322SO. The modification entailed the installation of a main deck side cargo door as part of a conversion of the airplane from a passenger configuration to a special freighter configuration. \n\n\tSince STC SA2322SO for Model 747-100 series airplanes is similar in design to STC SA4227NM-D for Model 747-200 series airplanes, the FAA has determined that the unsafe condition may also exist on a MODEL 747-200 series airplane that has been modified in accordance with STC SA4227NM-D. (Likewise, that STC entails the conversion of a Model 747-200 series airplane from a passenger configuration to a special freighter configuration.) \n\n\tSince the unsafe condition described is likely to exist or develop on other airplanes of the same type design, the FAA issued Telegraphic AD T96-01-51 to prevent malfunction of the safety interlock system of the main deck cargo door, which could result in the opening of the main deck side cargo door during flight, and subsequent rapid decompression of the airplane. The AD requires repetitive inspections of the latch safety pins of the main deck side cargo door to ensure that the door is securely latched and locked. The AD also requires deactivation of the "LATCHES UNLOCKED" light at the door operating panel, and the "DOOR UNLOCKED" light at theflight engineer (F/E) panel; as well as the fabrication and installation of a placard to indicate that the "DOOR UNLOCK" light at the F/E panel has been deactivated. These actions are required to be accomplished in accordance with a method approved by the FAA. \n\n\tThe AD also provides for the termination of these requirements following accomplishment of a modification that positively addresses the identified unsafe condition and that has been approved by the FAA. \n\n\tSince it was found that immediate corrective action was required, notice and opportunity for prior public comment thereon were impracticable and contrary to the public interest, and good cause existed to make the AD effective immediately by individual telegrams issued on January 3, 1996, to all known U.S. owners and operators of the affected Boeing Model 747-100 and -200 series airplanes. These conditions still exist, and the AD is hereby published in the Federal Register as an amendment to section 39.13 of the FederalAviation Regulations (14 CFR 39.13) to make it effective to all persons. \n\n\tThis is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.\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 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 Number 96-NM-01-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\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\n\t2. Section 39.13 is amended by adding the following new airworthiness directive: