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87-02-07: 87-02-07 BOEING: Amendment 39-5506. Applies to all Model 737-100 and 737-200 series airplanes, certificated in any category. To minimize the hazard of lower wing surface fuel tank access cover penetration due to impact from low energy engine debris, accomplish the following, unless already accomplished. \n\n\tA.\tWithin the next year after the effective date of this AD, replace the lower wing surface fuel tank access covers located immediately inboard and outboard of each engine (total of four per airplane), with covers having impact resistance equivalent to that of 2024-T3 aluminum 0.140-inch thick, as approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. The replacement covers must also be fire resistant, as defined in the Federal Aviation Regulations, Part 1. \n\n\tB.\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\tC.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of the modifications required by this AD. \n\n\tThis amendment becomes effective February 9, 1987.
93-06-01: 93-06-01 BOEING: Amendment 39-8526. Docket 92-NM-148-AD. Supersedes AD 84-21-02 R1, Amendment 39-6430.\n\n\tApplicability: Model 747 series airplanes, as listed in Section 3.0 of Boeing Document No. D6-35022, "Supplemental Structural Inspection Document" (SSID), Revision D, dated February 1992, certificated in any category.\n\n\tCompliance: Required as indicated, unless accomplished previously.\n\n\tTo ensure the continuing structural integrity of the total Boeing Model 747 fleet, accomplish the following:\n\n\t(a)\tFor airplanes listed in Boeing Document No. D6-35022, Revision C, dated April 1989: Within 3 months after February 12, 1990 (the effective date of AD 84-21-02 R1, Amendment 39-6430), incorporate a revision into the FAA-approved maintenance inspection program which provides no less than the required Damage Tolerance Rating (DTR) for each Structural Significant Item (SSI) listed in Boeing Document No. D6-35022, Revision C, dated April 1989. (The required DTR value for eachSSI is listed in the document.) The revision to the maintenance program shall include and be implemented in accordance with the procedures in Sections 5.0 and 6.0 of the SSID.\n\n\t(b)\tFor airplanes listed in Boeing Document No. D6-35022, Revision D, dated February 1992: Within 12 months after the effective date of this AD, replace the revision of the FAA-approved maintenance inspection program required by paragraph (a) of this AD with a revision that provides no less than the required DTR for each SSI listed in Boeing Document No. D6-35022, Revision D, dated February 1992. (The required DTR value for each SSI is listed in the document.) The revision to the maintenance program shall include and be implemented in accordance with the procedures in Sections 5.0 and 6.0 of the SSID.\n\n\t(c)\tCracked structure must be repaired, prior to further flight, in accordance with an FAA-approved method.\n\n\t(d)\tAn alternative method of compliance or adjustment of the compliance time that providesan acceptable level of safety may be used if approved by the Manager, Seattle 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, Seattle ACO.\n\n\tNOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.\n\n\t(e)\tSpecial flight permits may be issued in accordance with FAR 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 inspections shall be done in accordance with Boeing Document No. D6-35022, "Supplemental Structural Inspection Document (SSID)", Revision C, dated April 1989, and Boeing Document No. D6-35022, "Supplemental Structural Inspection Document (SSID)", Revision D, dated February 1992, comprised of Volumes I and II, which includes the following list of effective pages:\n\n\nPage Number\nRevision Ltr.\n\n\nList of Active Pages\nD\nPages 1 thru 21.1\n\n\n(NOTE: The issue date of Revision D is indicated only on the title page; no other page of the document is dated.) The incorporation by reference of Revision D was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. The incorporation by reference of Revision C 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 February 12, 1990 (55 FR 1005, January 11, 1990). Copies may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; 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 May 17, 1993.
2000-24-19: This amendment adopts a new airworthiness directive (AD), applicable to all Learjet Model 35, 35A, 36, and 36A series airplanes, that requires revision of the Airplane Flight Manual (AFM) to add procedures for donning the flightcrew oxygen masks when the cabin altitude warning horn is activated. This amendment is intended to prevent incapacitation of the flightcrew due to lack of oxygen and consequent loss of control of the airplane due to absence of AFM procedures for donning the flightcrew oxygen masks when the cabin altitude warning horn is activated.
94-01-10: 94-01-10 BOEING: Amendment 39-8792. Docket 92-NM-173-AD. Supersedes AD 91-20-09, Amendment 39-8043.\n \n\tApplicability: Model 757 series airplanes equipped with Pratt and Whitney PW2000 series engines, certificated in any category. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tNOTE 1: Paragraphs (a) and (b) of this AD restate the requirements of AD 91-20-09, Amendment 39-8043, paragraphs (a) and (b). As allowed by the phrase, "unless accomplished previously," if the requirements of AD 91-20-09 have been accomplished previously, paragraphs (a) and (b) of this AD do not require those actions to be repeated. \n\n\tNOTE 2: Paragraph (c) of this AD restates the requirement for repetitive inspections contained in paragraph (d) of AD 91-20-09, Amendment 39-8043. Paragraph (c) of this AD requires that the first inspection required by this AD must be performed within the specified repetitive inspection interval after the last inspection performed in accordance with paragraph (d) of AD 91-20-09. \n\n\tTo prevent deployment of a thrust reverser in flight and subsequent reduced controllability of the airplane, accomplish the following: \n\n\t(a)\tWithin 14 days after September 16, 1991 (the effective date of AD 91-20-09, Amendment 39-8043), accomplish either paragraph (a)(1) or (a)(2) of this AD. \n\n\t\t(1)\tAccomplish both paragraphs (a)(1)(i) and (a)(1)(ii) of this AD: \n\t\t\t(i)\tInspect the thrust reverser Directional Control Valve (DCV) assemblies of both engines to determine the solenoid-driven pilot valve's part number, in accordance with Boeing Alert Service Bulletin 757-78A0027, dated September 9, 1991.\n \n\t\t\t\t(A)\tIf any DCV has a suspect pilot valve as specified in the service bulletin, prior to further flight, replace the DCV with a DCV that has a part number of a non-suspect solenoid-driven pilot valve, in accordance with the service bulletin. \n\n\t\t\t\t(B)\tIf a DCV has a non-suspect solenoid-driven pilot valve as specified in the service bulletin, that pilot valve does not need to be replaced. \n\n\t\t\t(ii)\tPerform all tests and inspections of the engine thrust reverser control and indication system on both engines in accordance with Boeing Service Bulletin 757- 78-0025, dated September 9, 1991. Prior to further flight, correct any discrepancy found in accordance with the service bulletin. \n\n\t\t(2)\tAccomplish paragraph (a)(1) of this AD on one engine's thrust reverser and deactivate the other engine's thrust reverser, in accordance with Section 78-31-1 of Boeing Document D630N002, "Boeing 757 Dispatch Deviation Guide," Revision 8, dated January 15, 1991.\n \n\t(b)\tWithin 24 days after September 16, 1991 (the effective date of AD 91-20-09, Amendment 39-8043), the requirements of paragraph (a)(1) of this AD must be accomplished on both engines' thrust reverser systems. \n\n\t(c)\tRepeat the tests and inspections specified in paragraph (a)(1)(ii) at intervals not to exceed 3,000 flight hours, and prior to further flight following any maintenance that disturbs the thrust reverser control system. Prior to further flight, correct any discrepancy found in accordance with Boeing Service Bulletin 757-78-0025, dated September 9, 1991. \n\n\t(d)\tWithin 5 years after the effective date of this AD, install an additional thrust reverser system locking feature (sync lock installation), in accordance with Boeing Service Bulletin 757-78-0028, Revision 1, dated October 29, 1992, or Revision 2, dated January 14, 1993. \n\n\t(e)\tWithin 1,000 hours time-in-service after installing the sync lock required by paragraph (d) of this AD (either in production or by retrofit), or within 1,000 hours time-in- service after the effective date of this AD, whichever occurs later; and thereafter at intervals not to exceed 1,000 hours time-in-service: Perform functional tests of the sync lock in accordance with the "Thrust Reverser Sync Lock Integrity Test" procedures specified below. If any discrepancy is found during any test, prior to further flight, correct it in accordance with procedures described in the Boeing 757 Maintenance Manual. \n\n\t\t"THRUST REVERSER SYNC LOCK INTEGRITY TEST \n\n1.\tGeneral \n\tA.\tUse this procedure to test the integrity of the thrust reverser sync locks. \n\n2.\tThrust Reverser Sync Lock Test \n\tA.\tPrepare for the Thrust Reverser Sync Lock Test. \n\n\t\t(1)\tOpen the AUTO SPEEDBRAKE circuit breaker on the overhead \t\t\t\tcircuit breaker panel, P11. \n\n\t\t(2)\tDo the steps that follow to supply power to the thrust reverser system: \n\t\t\t(a)\tMake sure the thrust levers are in the idle position. \n\n\t\t\tCAUTION:\tDO NOT EXTEND THE THRUST REVERSER \t\t\t\t\t\tWHILE THE CORE COWL PANELS ARE OPEN. \t\t\t\t\tDAMAGE TO THE THRUST REVERSER AND \t\t\t\t\t\tCORE COWL PANELS CAN OCCUR. \n\n\t\t\t(b)\tMake sure the thrust reverser halves are closed. \n\t\t\t(c)\tMake sure the core cowl panels are closed. \t\t\t\t\t(d)\tPut the EEC MAINT POWER switch or the EEC POWER L \t\t\t\tand EEC POWER R switches to the ALTN position. \n\n\t\t\t(e)\tFor the left engine: \n\n\t\t\t\t1)\tPut the EEC MAINT CHANNEL SEL L switch to the \n\t\t\t\t\tAUTO position. \n\t\t\t\t2)\tPut the L ENG fire switch to the NORM position. \n\n\t\t\t(f)\tFor the right engine: \n\n\t\t\t\t1)\tPut the EEC MAINT CHANNEL SEL R switch to the \n\t\t\t\t\tAUTO position. \n\t\t\t\t2)\tPut the R ENG fire switch to the NORM position. \n\n\t\t\t(g)\tMake sure the EICAS circuit breakers (6 locations) are \t\t\t\t\tclosed. \n\n\t\t\tWARNING:\tTHE THRUST REVERSER WILL AUTOMATICALLY \n\t\t\t\t\tRETRACT IF THE ELECTRICAL POWER TO THE \n\t\t\t\t\tEEC/THRUST REVERSER CONTROL SYSTEM IS \n\t\t\t\t\tTURNED OFF OR IF THE EEC MAINT POWER \n\t\t\t\t\tSWITCH IS MOVED TO THE NORM POSITION. \t\t\t\t\tTHE ACCIDENTAL OPERATION OF THE THRUST \n\t\t\t\t\tREVERSER CAN CAUSE INJURY TO PERSONS \t\t\t\t\tOR DAMAGE TO EQUIPMENT CAN OCCUR. \n\n\t\t\t(h)\tMake sure these circuit breakers on the main power \t\t\t\t\tdistribution panel, P6, are closed: \n\n\t\t\t\t1)\tFUEL COND CONT L \n\t\t\t\t2)\tFUEL COND CONT R \n\t\t\t\t3)\tT/L INTERLOCK L \n\t\t\t\t4)\tT/L INTERLOCK R \n\t\t\t\t5)\tLEFT T/R SYNC LOCK6)\tRIGHT T/R SYNC LOCK \n\t\t\t\t7)\tL ENG ELECTRONIC ENGINE CONTROL ALTN \t\t\t\t\tPWR \n\t\t\t\t\t(if installed) \n\t\t\t\t8)\tR ENG ELECTRONIC ENGINE CONTROL ALTN \t\t\t\t\tPWR \n\t\t\t\t\t(if installed) \n\n\t\t\t(i)\tMake sure these circuit breakers on the overhead circuit \n\t\t\t\tbreaker panel, P11, are closed: \n\n\t\t\t\t1)\tAIR/GND SYS 1 \n\t\t\t\t2)\tAIR/GND SYS 2 \n\t\t\t\t3)\tLANDING GEAR POS SYS 1 \n\t\t\t\t4)\tLANDING GEAR POS SYS 2 \n\n\t\t\t(j)\tFor the left engine, make sure these circuit breakers on the \t\t\t\tP11 panel are closed: \n\n\t\t\t\t1)\tLEFT ENGINE PDIU \n\t\t\t\t2)\tLEFT ENGINE THRUST REVERSER CONT/SCAV \n\t\t\t\t\tPRESS \n\t\t\t\t3)\tLEFT ENGINE ELECTRONIC ENGINE CONTROL \n\t\t\t\t\tALTN PWR (if installed) \n\t\t\t\t4)\tLEFT ENGINE THRUST REVERSER PRI CONT 5)\n\t\t\t\t\tLEFT ENGINE THRUST REVERSER SEC CONT \n\n\t\t\t(k)\tFor the right engine, make sure these circuit breakers on the \n\t\t\t\tP11 panel are closed: \n\n\t\t\t\t1)\tRIGHT ENGINE PDIU \n\t\t\t\t2)\tRIGHT ENGINE THRUST REVERSER CONT/SCAV \n\t\t\t\t\tPRESS \n\t\t\t\t3)\tRIGHT ENGINE ELECTRONIC ENGINE CONTROLALTN PWR (if installed) \n\t\t\t\t4)\tRIGHT ENGINE THRUST REVERSER PRI CONT \n\t\t\t\t5)\tRIGHT ENGINE THRUST REVERSER SEC CONT \n\n\t\t\t(l)\tSupply electrical power. \n\n\t\t\t(m)\tRemove the pressure from the left (right) hydraulic system. \n\n\tB.\tDo the Thrust Reverser Sync Lock Test. \n\n\t\t(1)\tMove and hold the manual unlock lever on the center actuator on both \t\t\tthrust reverser sleeves to the unlock position. \n\t\t(2)\tMake sure the thrust reverser sleeves did not move. \n\t\t(3)\tMove the left (right) reverser thrust lever up and rearward to the idle \n\t\t\tdetent position. \n\t\t(4)\tMake sure both thrust reverser sleeves move aft (approximately 0.15 \t\t\tto 0.25 inch). \n\t\t(5)\tRelease the manual unlock lever on the center actuators. \n\n\n\t\tWARNING:\tMAKE SURE ALL PERSONS AND EQUIPMENT ARE \t\t\tCLEAR OF THE AREA AROUND THE THRUST REVERSER. WHEN YOU \t\tAPPLY \tHYDRAULIC PRESSURE THE THRUST REVERSER WILL EXTEND \t\tAND CAN CAUSE INJURIES TO PERSONS OR DAMAGE TO EQUIPMENT. \n\n\t\t(6)\tPressurize the left (right) hydraulic system. \n\t\t(7)\tMake sure the thrust reverser extends. \n\t\t(8)\tMove the left (right) reverser thrust lever to the fully forward and down \n\t\t\tposition to retract the thrust reverser.\n \n\tC.\tPut the Airplane Back to its Usual Condition. \n\n\t\t(1)\tRemove hydraulic pressure. \n\t\t(2)\tClose the left and right fan cowls. \n\t\t(3)\tClose the AUTO SPEEDBRAKE circuit breaker on the P11 panel. \n\t\t(4)\tRemove electrical power if it is not necessary. \n\n\tD.\tRepeat the Thrust Reverser Sync Lock Test on the other engine." \n\n\t(f)\tInstallation of the sync lock, as required by paragraph (d) of this AD, constitutes terminating action for the requirements of paragraphs (a) through (c) of this AD. \n\n\t(g)\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, Seattle 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, Seattle ACO. \n\n\tNOTE 3: Approvals of alternative methods of compliance issued for AD 91-20-09 constitute valid approvals for compliance with the requirements of paragraphs (a) through (c) of this AD. \n\n\tNOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\n\t(h)\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the airplane to a location where the requirements of this AD can be accomplished. \n\n\t(i)\tThe actions shall be done in accordance with Boeing Alert Service Bulletin 757- 78A0027, dated September 9, 1991; Boeing Service Bulletin 757-78-0025, dated September 9, 1991; Boeing Document D630N002, "Boeing 757 Dispatch Deviation Guide," Revision 8, dated January 15, 1991; Boeing Service Bulletin 757-78-0028, Revision 1, dated October 29, 1992; andBoeing Service Bulletin 757-78-0028, Revision 2, dated January 14, 1993. The incorporation by reference of Boeing Alert Service Bulletin 757-78A0027, dated September 9, 1991; Boeing Service Bulletin 757-78-0025, dated September 9, 1991; Boeing Document D630N002, "Boeing 757 Dispatch Deviation Guide," Revision 8, dated January 15, 1991; 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 September 16, 1991 (56 FR 46725, September 16, 1991). The incorporation by reference of the remainder of the service documents listed above is 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 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. \n\n\t(j)\tThis amendment becomes effective on March 3, 1994.
2019-18-01: The FAA is adopting a new airworthiness directive (AD) for certain International Aero Engines AG (IAE) V2500 model turbofan engines. This AD was prompted by an inspection that determined that material anomalies exist in certain low-pressure turbine (LPT) stage 6 disks. This AD requires removal from service of the affected LPT stage 6 disks and their replacement with a part eligible for installation. The FAA is issuing this AD to address the unsafe condition on these products.
97-11-01: This amendment adopts a new airworthiness directive (AD), applicable to certain Airbus Model A320 series airplanes, that requires an initial inspection of fastener holes on certain outer frames of the fuselage to detect fatigue cracking, and modification of this area by cold expanding these holes and installing oversized fasteners. This amendment is prompted by a report from the manufacturer indicating that, during full-scale fatigue testing of the test article, fatigue cracking was detected in the area where the center fuselage joins the wing. The actions specified by this AD are intended to prevent fatigue cracking and consequent reduced structural integrity of this area, which could lead to rapid depressurization of the fuselage.
2007-05-16: This action supersedes emergency airworthiness directive (AD) 2007-04-51 that was sent previously to all known U.S. owners and operators of GE CF34-3A1/-3B/-3B1 turbofan engines. That action required a onetime visual and tactile inspection of certain areas of certain serial number (SN) fan disks for an arc-out defect, within 20 engine flight hours after the effective date of that AD. This AD supersedes AD 2007-04-51 and adds eight SNs to the list of suspect fan disks. This AD results from GE discovering eight additional SNs of fan disks suspected of having an arc-out defect, and from the original report that a GE CF34-3B1 turbofan engine experienced an uncontained fan disk failure during flight operation. We are issuing this AD to prevent an uncontained fan disk failure and airplane damage.
80-17-11: 80-17-11 GATES LEARJET: Amendment 39-3888. Applies to the following model and serial number airplanes: Model 35 Series Serial Number 35-050 through 35-339 except 35-054 and 35-065 Model 36 Series Serial Number 36-017 through 36-045 COMPLIANCE: Required as indicated unless already accomplished. To prevent encountering a possible overload flight condition that could fail the forward engine mount, accomplish the following: A) Within the next 75 hours time-in-service after the effective date of this AD, in accordance with Gates Learjet Corporation Service Bulletin 35/36-11-3, dated July 28, 1980: 1. Install airspeed warning placards and modify the Mach/overspeed switch circuit to effect a reduced maximum operating airspeed (VMO) of 307 KIAS, from sea level to 31,100 feet altitude. 2. Insert in the existing Airplane Flight Manual the temporary Airplane Flight Manual Supplement included in Service Bulletin 35/36-11-3. B) Within the next 600 hours' time-in-service after the effective date of this AD, replace or re-age both forward engine mounts in accordance with Gates Learjet Corporation Airplane Modification Kit AMK 80-6. Accomplish the removal and installation of the engine mounts at authorized Gates Learjet Service Centers and the nondestructive testing and heat treating at appropriately rated FAA certified repair stations. C) Upon compliance with Paragraph B above, the requirements of Paragraph A of this AD are no longer applicable. D) Issuance of a Special Flight Permit in accordance with FAR 21.197 is permitted for the purpose of moving the affected airplanes to a location where the modifications required by this AD can be accomplished. E) Any equivalent means of compliance with this AD must be approved by the Chief, Aircraft Certification Program, Federal Aviation Administration, Room 238, Terminal Building No. 2299, Mid-Continent Airport, Wichita, Kansas 67209. This amendment becomes effective August 28, 1980.
2019-16-12: The FAA is superseding Airworthiness Directive (AD) 2005-20- 01, which applied to all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. AD 2005-20-01 required repetitive inspections of the vertical stiffeners at left buttock line (LBL) and right buttock line (RBL) 6.15 for cracks; and replacement of both stiffeners with new, improved stiffeners if any stiffener is found cracked. This new AD requires, depending on airplane configuration, replacing the vertical stiffeners at LBL and RBL 6.15 on the rear spar of the wing center section, installing angle and bonding jumpers, installing brackets, applying sealant, and applying paint. This AD was prompted by reports of cracks found in the left and right side keel beam upper chords when replacing vertical stiffeners. This AD was also prompted by possible degradation of the fault current bonding path that could introduce an ignition source in the fuel tank in the event of a fault current being imparted onto the fuel tank structure. The FAA is issuing this AD to address the unsafe condition on these products.
77-07-05: 77-07-05 HILLER AVIATION: Amendment 39-2862 as amended by Amendment 39-2917. Applies to Hiller Model UH-12, UH-12A, UH-12B, UH-12C, UH-12D, UH-12E UH-12E (4- place), (including military Models H-23A, H-23B, H-23C, H-23D, H-23F, OH-23G, HTE-1, HTE-2, and CH112) helicopters, certificated in all categories. Compliance required as indicated, unless already accomplished. To detect cracks in the control rotor blade spar tube and cuff and to establish a service life of 6860 hours for Hiller P/N 36124 cuff used with unfaired paddles accomplish the following: (a) Within the next 100 hours time in service after the effective date this AD, unless already accomplished within the last 100 hours time in service and thereafter at intervals not to exceed 100 hours time in service from the last inspection, inspect, replace or repair the control rotor blade spar tube and cuff in accordance with Hiller Aviation Service Bulletin No. 36-1, Revision 2, dated June 19, 1974, or later FAA-approved revisions. (b) After any repair is accomplished in accordance with Hiller Aviation Service Bulletin No. 36-1, Revision 2, dated June 19, 1974 or later FAA-approved revisions, the control rotor blade spar tube (faired and unfaired) and cuff must be retired before 2500 additional hours time in service after rework or when the current approved total service life (total service life before repair plus service life after repair) is reached, whichever comes first. (c) Fabric covered, metal covered, faired and unfaired control rotor blades are not interchangeable and must not be intermixed. (d) For Hiller P/N 36124 cuffs used with unfaired paddles (1) Cuffs with more than 6660 hours time in service, remove and replace with a serviceable part within 200 hours time in service after the effective date of this AD. (2) Cuffs with less than 6660 hours time in service, remove and replace with a serviceable part prior to 6860 hours time in service. (3) For cuffs for which the prior service history cannot be documented, within the next 25 hours time in service, unless already accomplished within the last 25 hours time in service prior to the effective date of this AD and at intervals not to exceed 50 hours time in service, perform a dye penetrant inspection of the cuff per Hiller Aviation Service Bulletin, No. 36-1, Revision 2, dated June 19, 1974, or later FAA approved revisions. Remove cracked cuffs from service prior to further flight. Cuffs for which the prior service history cannot be documented cannot be used as a replacement part. Remove from service all cuffs prior to the accumulation of 225 hours total time in service since April 7, 1977. (e) Equivalent inspection procedures and repair procedures for Hiller P/N 36124 cuff when used only with unfaired paddles may be approved by the Chief,Aircraft Engineering Division, FAA Western Region. (f) Special flight permits may be issued in accordance with FAR's 21.197 and 21.199 tooperate helicopters to a base for accomplishment of the inspections required by this AD. Amendment 39-2862 superseded Amendment 39-1990 (39 F.R. 36855), AD 74-21-05. Amendment 39-2862 became effective April 7, 1977. This amendment 39-2917 becomes effective June 20, 1977.