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91-12-03: 91-12-03 BOEING: Amendment 39-7014. Docket 91-NM-100-AD. \n\n\tApplicability: Model 757, 747-400, and 767 series airplanes; as listed in Boeing Service Bulletins 757-26A0026, 747-26A2180, 767-26A0075, and 767-26-0076, each dated March 28, 1991, and 757-26-0027, Revision 1, dated April 11, 1991; certificated in any category. \n\n\tCompliance: Required within 30 calendar days after the effective date of this AD, unless previously accomplished. \n\n\tTo prevent reduced or blocked discharge of fire extinguishing agent from the cargo compartment metered system, and to prevent false indications of low pressure in the initial discharge system, accomplish the following: \n\n\t(a)\tDetermine the part number and serial number of each cargo compartment fire extinguishing agent container by inspection of aircraft records or visual inspection of the containers. If the part number and serial number are listed in Appendix 1 of Pacific Scientific HTL/Kin-Tech Division Alert Service Bulletin 26A1100, Revision 1, dated April 3, 1991, prior to further flight, replace the container with one having a part number and serial number not listed in that Pacific Scientific HTL service bulletin. If the part number and serial number are not listed in that Pacific Scientific HTL service bulletin, no further action is required. \n\n\t(b)\tAn alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\tNOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Seattle ACO. \n\n\t(c)\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. \n\n\tThe required inspections shall be conducted on those airplanes listed in the "Effectivity" sections of Boeing Service Bulletins 757-26A0026, 747-26A2180, 767-26A0075, and 767-26- 0076, each dated March 28, 1991; and Boeing Service Bulletin 757-26-0027, Revision 1, dated April 11, 1991. Part numbers and serial numbers of the cargo compartment fire extinguishing agent containers installed on the airplane shall be compared against the listing of part numbers and serial numbers of potentially contaminated containers contained in Appendix 1, pages 1 through 15, of Pacific Scientific, HTL/Kin-Tech Division, Alert Service Bulletin 26A1100, Revision 1, dated April 3, 1991. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. Copies may be inspected at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington; or at the Office of the Federal Register, 1100 L Street N.W., Room 8401, Washington, D.C. \n\n\tThis amendment (39-7014, AD 91-12-03) becomes effective on June 19, 1991.
92-10-13 R1: 92-10-13 R1 MCDONNELL DOUGLAS: Amendment 39-9614. Docket 95-NM-127-AD. Revises AD 92-10-13, Amendment 39-8247. \n\n\tApplicability: Model DC-9-80 series airplanes and Model MD-88 airplanes equipped with digital flight guidance computers (DFGC) having part numbers prior to 4034241-972; 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 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 request approval for an alternative method of compliance in accordance with paragraph (d) 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 as indicated, unless accomplished previously. \n\n\tTo prevent automatic thrust lever advance on a surging engine during takeoff, which could cause engine failure, accomplish the following: \n\n\t(a)\tWithin 30 days after May 20, 1992 (the effective date of AD 92-10-13, amendment 39-8247), 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 in the AFM. \n\n\t"LIMITATIONS SECTION \n\n\tAutothrottles must be disconnected if engine surge (stall) is detected during takeoff." \n\n\t(b)\tWithin 30 days after May 20, 1992 (the effective date of AD 92-10-13, amendment 39-8247), revise the Procedures Section of the FAA-approved AFM to include the following statement. This may be accomplished by inserting a copy of this AD in the AFM. \n\n"PROCEDURES SECTION \n\n\t\t\t\tCAUTION \n\nDuring takeoff, theDigital Flight Guidance Computer (DFGC) engine failure logic is armed if (1) the flight director pitch axis is in takeoff mode, (2) the aircraft is above 400 feet radio altitude, and (3) both engine pressure ratios (EPR's) are below the go-around EPR limit. If the DFGC detects an EPR drop greater than or equal to 0.25 EPR and 7% N1 from the same engine, as compared to the other engine, the engine failure logic is satisfied and the DFGC will change the Thrust Rating Panel (or indicator) thrust limit to Go-Around (GA). This will cause the autothrottle system to unclamp and enter normal EPR limit (EPR LIM) mode where the throttles will maintain the higher engine EPR at the selected go-around thrust rating EPR LIM. Such an EPR and N1 drop may also result from an engine surge (stall). Advancing thrust levers on a surging engine will hinder surge recovery and may result in eventual engine failure. \n\nIf an engine surge (stall) is detected during takeoff: \n\n\t(1)\tDisconnect autothrottles. \n\n\t(2)\tReduce thrust on affected engine (idle if necessary). \n\n\t(3)\tShut down the affected engine if surging and popping continues. \n\n\t(4)\tIf affected engine surging or popping stops, accomplish the following: \n\n\t\tA. Place ignition switch to GRD START & CONTIN. \n\n\t\tB. Place ENG anti-ice switches to ON. \n\n\t\tC. Place PNEU X-FEED VALVE lever OPEN on affected side. \n\n\t\tD. Place AIR FOIL anti-ice switches ON. \n\n\t\tE. Advance affected throttle slowly. \n\n\t(5)\tIf engine surging or popping returns, turn the ENG anti-ice switch OFF. \n\n\t(6)\tAfter normal operation has been established, the autothrottles may be re-engaged. \n\n\tNOTE: A NO MODE light may be annunciated due to abnormal bleed configuration." \n\n\t(c)\tReplacement of both DFGC's having a part number prior to 4034241-972, with DFGC's having part number 4034241-972, in accordance with McDonnell Douglas Service Bulletin MD80-22-111, dated May 23, 1995, constitutes terminating action for the requirements of thisAD. Once the replacements are accomplished, the AFM revisions required by paragraphs (a) and (b) of this AD may be removed. \n\n\tNOTE 2: McDonnell Douglas Service Bulletin MD80-22-111, dated May 23, 1995, references Honeywell Service Bulletin 4034241-22-44, dated May 22, 1995, as an additional source of service information. \n\n\tNOTE 3: Paragraph 1.B of McDonnell Douglas Service Bulletin MD80-22-111, dated May 23, 1995, specifies certain concurrent actions that affect airplanes equipped with DFGC's having part numbers prior to 4034241-971. \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, Los Angeles Aircraft Certification Office (ACO), FAA, Transport 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, Los Angeles ACO. \n\n\tNOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles 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)\tThe replacement shall be done in accordance with McDonnell Douglas Service Bulletin MD80-22-111, dated May 23, 1995. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Technical Publications Business Administration, Department C1-L51 (2-60). Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Los Angeles Aircraft Certification Office, Transport Airplane Directorate, 3960 Paramount Boulevard, Lakewood, California; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(g)\tThis amendment becomes effective on June 13, 1996.
2009-19-03: We are adopting a new airworthiness directive (AD) for the products listed above that will supersede an existing AD. This AD results from mandatory continuing airworthiness information (MCAI) issued by the aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: BAE Systems have been notified by the main landing gear (MLG) radius rod manufacturer, APPH Ltd, that a batch of incorrectly manufactured Buffer Springs (part number 184818) has been supplied to their parts distributor and maintenance and repair organisation (MRO) facilities in North America. There is a risk that any radius rod fitted with one of these incorrectly manufactured Buffer Springs could jam in an unlocked position. This condition, if not corrected, could result in MLG collapse and consequent injury to occupants of the aeroplane. EASA issued AD 2009-0121-E to require the replacement of the affected radius rods. BAE Systems (Operations) Ltd Alert Service Bulletin (ASB) 32-A- JA090640 Revision 2 (the ASB) has now been issued, which identifies an additional seven affected radius rods by serial number (s/n). This AD requires actions that are intended to address the unsafe condition described in the MCAI. DATES: This AD becomes effective October 5, 2009. On October 5, 2009, the Director of the Federal Register approved the incorporation by reference of British Aerospace Jetstream Series 3100 and 3200 Alert Service Bulletin 32-A-JA090640, Revision 2, dated August 11, 2009, listed in this AD. As of June 26, 2009 (74 FR 29936, June 24, 2009), the Director of the Federal Register approved the incorporation by reference of British Aerospace Jetstream Series 3100 and 3200 Alert Service Bulletin 32-A- JA090640, dated June 2009 (includes an attached Accomplishment Report), and APPH Ltd. Service Bulletins 1847-32-14 and 1862-32-14, as applicable, both dated June 2009, listed in this AD.We must receive comments on this AD by October 29, 2009.
85-12-01 R1: 85-12-01 R1 BOEING: Amendment 39-5073 as amended by Amendment 39-5439. Applies to Model 707/720 series airplanes, certificated in all categories. Compliance is required as indicated in the body of the AD. \n\n\tTo ensure continuing structural integrity, accomplish the following, unless already accomplished: \n\n\tA.\tWithin 180 days after the effective date of the amendment, incorporate a revision into the FAA-approved maintenance inspection program which requires accomplishment of the inspection and repairs, as necessary, of each Significant Structural Detail (SSD) as listed in Boeing Document D6-44860, Supplemental Structural Inspection Document (SSID), Revision M, or later FAA-approved revision. The revision to the maintenance program must include procedures to notify the manufacturer when SSD's are found cracked. The inspection thresholds, repetitive inspection intervals, inspection techniques, and terminating action for each SSD are listed in the SSID. Incorporate this revision to the maintenance program in accordance with paragraphs B., C., and D., below. \n\n\tB.\tThe increase of inspection intervals in accordance with Section 5.2 of Boeing Document D6-44860, Revision M, is not permitted, except as provided in paragraphs F. and G., below. \n\n\tC.\tInspect each Significant Structural Detail (SSD) which has exceeded the initial threshold specified in Boeing Document D6-44860, Revision M, within 180 days after the effective date of this amendment. Significant Structural Details which are below the inspection thresholds specified in Boeing Document D6-44860, Revision M, must have an initial inspection within 180 days after the effective date of this amendment or prior to reaching the threshold, whichever is later. Accomplish these inspections in accordance with Boeing Document D6- 44860, Revision M, or later FAA-approved revisions. \n\n\tD.\tIf cracks are found, prior to further flight: (1) replace with a serviceable FAA approved part of the same part number, or an FAA approved replacement part provided by the manufacturer; or (2) repair in accordance with the Boeing Structural Repair Manual or repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\tE.\tAircraft may be ferried to a maintenance base for repair in accordance with FAR 21.197 and 21.199. \n\n\tF.\tAlternate means of compliance which provide an acceptable level of safety may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\tG.\tUpon request of the operator, an FAA Principal Maintenance Inspector, subject to prior approval of the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, may adjust the repetitive inspection intervals specified in this AD, if the request contains substantiating data to justify the increase for that operator. \n\n\tH.\tOperators who have acceptably incorporated the requirements of paragraphA., above, into their approved maintenance program, including the limitations listed in paragraphs B., C. and D., above, are exempt from the provisions of this AD. \n\n\tI.\tSignificant Structural Details (SSD) which are the subject of separate AD action are exempted from the requirements of this AD. \n\n\tAll persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to the Boeing Commercial Airplane Company, P.O. Box 3707, Seattle, Washington 98124-2207. These documents may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or the Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington. \n\n\tAmendment 39-5073 became effective July 5, 1985. \n\tThis amendment, 39-5439, becomes effective November 14, 1986.
69-03-02: 69-03-02\tBOEING: Amdt. 39-718 as amended by Amendment 39-949. Applies to Models 707, 720, and 727 airplanes listed in Service Bulletin Nos. 2536, dated 1 June 1967, as revised by Revision 1, 23 January 1970 and Service Bulletin 27-100 dated 8 June 1967, or later FAA approved revisions. \n\tCompliance required as indicated. \n\tA)\tWithin the next 2,500 hours time in service after 1 March 1969, unless already accomplished, for those aircraft listed in Boeing Service Bulletin No. 2536, dated 1 June 1967, for Model 707's and 720's or Boeing S.B. No. 27-100 dated 8 June 1967 for 727's, or later FAA approved revision, remove the existing rudder pedal adjustment crank assembly and replace with a modified or new crank assembly in accordance with Boeing Service Bulletin No. 2536, dated 1 June 1967, for Model 707's and 720's or Boeing Service Bulletin No. 27-100, dated 8 June 1967, for Model 727's or later FAA approved revisions or an equivalent design approved by the Chief, Aircraft EngineeringDivision, FAA Western Region. \n\tB)\tWithin the next 1,000 hours' time in service after the effective date of this amendment to Amendment 39-718 (34 F.R. 1769), AD 69-03-02, for those additional Model 707's and 720's listed in Revision 1, dated 23 January 1970, to Boeing Service No. 2536, and not previously listed in S.B. No. 2536, unless already accomplished, remove the existing rudder pedal adjustment crank assembly, and replace with a modified or new crank assembly, in accordance with Boeing S.B. No. 2536, Revision 1, dated 23 January 1970, or later FAA approved revisions, or an equivalent design approved by Chief, Aircraft Engineering Division, FAA Western Region. \n\tAmendment 39-718 effective March 1, 1969. \n\tThis amendment (39-949) becomes effective March 6, 1970.
89-23-52: 89-23-52 BOEING: Amendment 39-6500. Final copy of telegraphic AD. Docket No. 89-NM- 231-AD. \n\n\tApplicability: Model 737-300 and -400 series airplanes, line numbers 1770 to 1783, 1785, and 1787 to 1789, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\n\tTo prevent the loss of the forward entry door and subsequent rapid decompression of the airplane, accomplish the following: \n\n\tA.\tWithin 24 hours (clock hours, not flight hours) after the effective date of this amendment, incorporate the following limitation into the Limitations Section of the FAA- approved Airplane Flight Manual (AFM). This may be accomplished by inserting a copy of this AD in the AFM. \n\n\t\t"Airplane Pressurization \n\t\tDo not exceed 4.7 psi cabin pressure differential." \n\n\tB.\tWithin 20 flights after the effective date of this amendment, inspect the forward left entry door, fuselage aft frame, bottom door stop fitting at body station (BS) 349, waterline (WL) 216, left buttock line (LBL) 65, for missing bolts (two) attaching the inboard side of the door stop fitting to the fitting support intercostal. \n\n\t\t1.\tIf two bolts are found, the AFM limitations required by paragraph A., above, may be removed and no further action is required. \n\n\t\t2.\tIf one or both bolts are missing, inspect and repair prior to further flight, in accordance with a method approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. The AFM limitations required by paragraph A., above, may be removed and no further action is required. \n\n\tC.\tWithin 10 days after completion of the inspection required by paragraph B., above, for each airplane, submit a report of inspection findings, positive or negative, to the Manager, Seattle Manufacturing Inspection District Office, 7300 Perimeter Road South, Seattle, Washington 98108. This report must include the model of the airplane inspected, the date of inspection, and the numberof bolts installed. \n\n\tD.\tAn alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\tNOTE: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who will either concur or comment, and then send it to the Manager, Seattle Aircraft Certification Office. \n\n\tE.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. \n\n\tThis amendment (39-6500, AD 89-23-52) becomes effective on February 16, 1990, as to all persons, except those persons to whom it was made immediately effective by telegraphic AD T89-23-52, issued November 3, 1989, which contained this amendment.
90-21-15: 90-21-15 BOEING: Amendment 39-6767. Docket No. 90-NM-75-AD. \n\n\tApplicability: Model 737 series airplanes, listed in Boeing Alert Service Bulletin 737- 55A1031, Revision 2, dated November 30, 1989, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\n\tTo detect cracking in the horizontal stabilizer center section rear spar upper chord, accomplish the following: \n\n\tA.\tPrior to the accumulation of 35,000 landings, or within 350 landings after October 18, 1982 (the effective date of AD 82-21-02, Amendment 39-4473), whichever occurs later, unless accomplished within the last 4,150 landings, and thereafter at intervals not to exceed 4,500 landings since the last inspection, eddy current or dye penetrant inspect the upper surface of the forward flange of the horizontal stabilizer center section rear spar upper chord for cracks in the area of each beam gusset plate in accordance with "Part A-Inspection" of Boeing Alert Service Bulletin 737-55A1031, Revision 2, dated November 30, 1989, or previous FAA- approved revisions. If cracks are found, repair, modify, or replace the damaged chord before further flight, in accordance with Boeing Model 737 Structural Repair Manual, Subject 51-30-09, or Boeing Alert Service Bulletin 737-55A1031, Revision 2, dated November 30, 1989, or previous FAA-approved revisions. \n\n\tB.\tAfter repair, modification, or replacement, resume the repetitive inspections required by paragraph A. of this AD, at the following schedule or within the next 1,000 landings, whichever occurs later: \n\n\t\t1.\tPrior to the accumulation of 9,000 landings after repair.\n \n\t\t2.\tPrior to the accumulation of 35,000 landings after modification. \n\n\t\t3.\tPrior to the accumulation of 50,000 landings after replacement. \n\n\tThereafter, repeat the inspections at intervals not to exceed 4,500 landings. \n\n\tC.\tAn alternate means of compliance or adjustment of the compliance time, which provides an acceptable levelof safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\tNOTE: The request should be submitted directly to the Manager, Seattle ACO, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Seattle ACO. \n\n\tD.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. \n\n\tAll persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington 98055-4056. \n\n\tAirworthiness Directive 90-21-15 supersedes AD 82-21-02, Amendment 39-4473.This amendment (39-6767, AD 90-21-15) becomes effective on November 16, 1990.
90-09-04: 90-09-04 MCDONNELL DOUGLAS: Amendment 39-6584. Docket No. 89-NM-240-AD. \n\n\tApplicability: McDonnell Douglas Model DC-9-81, -82, -83, and -87 series airplanes and Model MD-88 airplanes, Fuselage Numbers 1071 through 1644, certificated in any category. \n\n\tCompliance: Required within 18 months after the effective date of this airworthiness directive (AD), unless previously accomplished. \n\n\tTo eliminate a potential fire ignition source in the main cabin above the overhead stowage compartment area, accomplish the following: \n\n\tA.\tVisually inspect the left and right overhead stowage compartment rail assemblies in the vicinity of each electrical bonding strap for evidence of arcing, burning, or chafing to electrical wiring. If damage is found, prior to further flight, repair the electrical wires in accordance with McDonnell Douglas MD-80 Maintenance Manual, Chapters 20-50-01 and 20-50-02. \n\n\tB.\tModify the electrical bonding strap installation of the left and right overhead stowage compartment rail assemblies in accordance with the Accomplishment Instructions of McDonnell Douglas MD-80 Alert Service Bulletin A25-309, dated October 30, 1989. \n\n\tC.\tAn alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\tNOTE: The request should be forwarded through an FAA Principal Avionics Inspector (PAI), who will either concur or comment and then send it to the Manager, Los Angeles Aircraft Certification Office. \n\n\tD.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. \n\n\tAll persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Business Unit Manager, Technical Publications, C1-HCW (54-60). These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or at the Los Angeles Aircraft Certification Office, 3229 East Spring Street, Long Beach, California. \n\n\tThis amendment (39-6584, AD 90-09-04) becomes effective on May 29, 1990.
2021-20-12: The FAA is adopting a new airworthiness directive (AD) for certain Leonardo S.p.a. Model AB139, AW139, AB412, and AB412 EP helicopters. This AD was prompted by failure of an Emergency Flotation System (EFS) float compartment to inflate during maintenance of the EFS. This AD requires inspecting certain EFSs and depending on the results, marking certain parts or removing certain parts from service, as specified in a European Union Aviation Safety Agency (EASA) AD, which is incorporated by reference. The FAA is issuing this AD to address the unsafe condition on these products.
91-06-12: 91-06-12 BOEING: Amendment 39-6938. Docket No. 90-NM-194-AD. \n\n\tApplicability: Model 757 series airplanes listed in Boeing Alert Service Bulletin 757- 52A0049, dated July 5, 1990, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\n\tTo ensure left and right passenger door Number 4 opening when required for emergency use, accomplish the following: \n\n\tA.\tPrior to the accumulation of 2,000 flight cycles, or within the next 100 flight cycles after the effective date of this AD, whichever occurs later, inspect the left and right Number 4 passenger door upper and lower hinge arm leaf springs for cracks and fractures, in accordance with Boeing Alert Service Bulletin 757-52A0049, dated July 5, 1990. \n\n\tB.\tIf cracked or fractured leaf springs are found as a result of the inspection required by paragraph A. of this AD, prior to further flight, accomplish either paragraph B.1. or B.2., below: \n\n\t\t1.\tReplace cracked or fracturedleaf springs in accordance with Section III. of the service bulletin; or \n\n\t\t2.\tReplace the cracked or fractured leaf springs with new steel leaf springs in accordance with an FAA-approved method, and reinspect those springs prior to the accumulation of an additional 2,000 flight cycles and thereafter at intervals not to exceed 500 flight cycles until the terminating action, required by paragraph D. of this AD, is accomplished. \n\n\tC.\tRepeat the inspection required by paragraph A. of this AD at the following intervals. \n\n\t\t1.\tFor airplanes with less than 5,000 flight cycles at the time of the last inspection: accomplish the next inspection within the next 500 flight cycles. \n\n\t\t2.\tFor airplanes with 5,000 or more flight cycles at the time of the last inspection: accomplish the next inspection within the next 150 flight cycles. \n\n\tD.\tWithin the next 18 months after the effective date of this AD, replace the upper and lower hinge arm steel leaf springs with titanium leaf springs for the left and right Number 4 passenger door, in accordance with Section III., of Boeing Alert Service Bulletin 757-52A0049, dated July 5, 1990. Such replacement constitutes terminating action for the repetitive inspections required by this AD. \n\n\tE.\tAn alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\tNOTE: The request should be submitted directly to the Manager, Seattle ACO, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Seattle ACO. \n\n\tF.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. \n\n\tAll persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington. \n\n\tThis amendment (39-6938, AD 91-06-12) becomes effective on April 18, 1991.