Results
63-05-03: 63-05-03 SNOW: Amdt. 541 Part 507 Federal Register March 2, 1963. Applies to Model S-2 Aircraft Serial Numbers 1003 Through 1162. Compliance required as indicated. (a) Within 10 hours' time in service after the effective date of this AD, inspect the wing main spar upper and lower spar web flange for cracks in the vicinity of the wing-fuselage attach points (approximately wing Station 19), using at least a 10-power glass. (b) If cracks are found, repair prior to further flight in accordance with Snow Service Letter No. 23 or FAA Engineering and Manufacturing Branch approved equivalent. (c) If no cracks are found, repeat the inspection specified in (a) at intervals not to exceed 25 hours' time in service from the previous inspection. (d) The repetitive inspection required by (c) may be discontinued when the modification set forth in Snow Service Letter No. 23 or an FAA Engineering and Manufacturing Branch approved equivalent is incorporated. This directive effective March 8, 1963.
47-21-23: 47-21-23 REPUBLIC: (Was Service Note 3 of AD-769-2.) Applies to Model RC-3 Aircraft with Engine Serial Numbers 23001 to 24083, Inclusive. Compliance required before the next flight and after 5 hours of operation following each installation of fan. Inspect the engine cooling fan capscrews for tightness. If tab locks are installed ascertain whether the locks are still in place. If the capscrews or the locks have loosened remove the capscrews, fan and pulley sheave. Clean and inspect parts for wear. Reassemble carefully using P/N 17778 drilled head capscrews with plain washers. Torque to 20 foot-pounds, operate engine up to 1,500 r.p.m. for 5 minutes, retorque and safety with 0.041-inch stainless steel wire. Visually inspect locking wire and capscrews after 5 hours of operation. Reassemble in this manner every time the fan is removed. Obtain the new capscrews, washers, and wire from your Seabee distributor or the engine manufacturer. (Franklin Service Bulletin No. 57 dated June 9, 1947, which supersedes Bulletin No. 50 covers this same subject.)
2005-13-26: The FAA is adopting a new airworthiness directive (AD) for certain Airbus models, as specified above. This AD requires installing safety signs on all passenger/crew doors, emergency exit doors, and cargo compartment doors. This AD is prompted by a report of injuries occurring on in-service airplanes when crewmembers forcibly initiated opening of passenger/crew doors against residual pressure causing the doors to rapidly open. We are issuing this AD to ensure that crewmembers are informed of the risks associated with forcibly opening passenger/crew, emergency exit, and cargo doors before an airplane is fully depressurized, which will prevent injury to crewmembers, and subsequent damage to the airplane caused by the rapid opening of the door.
2018-08-01: We are adopting a new airworthiness directive (AD) for Airbus Helicopters Model EC225LP helicopters. This AD requires inspecting each main rotor rotating swashplate (swashplate) control rod attachment yoke (yoke). This AD is prompted by a finding that the yoke is susceptible to cracking. The actions of this AD are intended to address an unsafe condition on these products.
2018-07-18: We are superseding Airworthiness Directive (AD) 2015-19-12, which applied to certain The Boeing Company Model 767 airplanes. AD 2015-19-12 required a general visual inspection of certain lap splices for missing fasteners, and all applicable related investigative and corrective actions. This AD retains the actions required by AD 2015-19- 12 and revises the applicability by adding airplanes. This AD was prompted by reports indicating that certain fasteners were not installed in a certain stringer lap splice on certain airplanes. We are issuing this AD to address the unsafe condition on these products.
62-26-01: 62-26-01 DOUGLAS: Amdt. 517 Part 507 Federal Register December 8, 1962. Applies to All C54-DC Series and DC-4 Aircraft Equipped With Pratt & Whitney Aircraft Twin Wasp Series and R-2000 Series Engines and Hamilton Standard 23E50/6507-0 Propellers. \n\n\tCompliance required within the next 200 hours' time in service after the effective date of this AD. \n\n\tRecent resurveys of 23E50/6507-0 propeller blade vibration stresses have shown that vibration stresses in excess of allowable limits for continuous safe operation occur over a wider range of engine operating speeds than was determined by previous surveys. To prevent possible blade failures due to exceeding allowable stress limits within this speed range, the following is required: \n\n\t(a)\tRemove the existing placard covering the 1,600 to 1,700 r.p.m. range and install a new placard in full view of the pilot to read: \n\n\t\t"During flight, avoid operation between 1,550 and 1,750 r.p.m. During ground running, avoid operation between 1,550 and 1,800 r.p.m. when the blades are off the low pitch stops." \n\n\t(b)\tMark the tachometers with a red arc over the 1,550 and 1,750 r.p.m. range. \n\n\t(c)\tRevise the operating limitations section of the FAA approved Airplane Flight Manual to incorporate the limitations in (a) and (b). \n\n\tNOTE: The other restricted operating speed range between 2,310 and 2,510 r.p.m. required by AD 56-20-05 still remains in effect. For the purpose of this directive, a single placard reading: "During flight, avoid operation between 1,550 and 1,750 r.p.m. and between 2,310 and 2,510 r.p.m.", in the first sentence, may be installed if desired. Similar wording may be used for the FAA approved Airplane Flight Manual. \n\n\tThis directive effective January 8, 1963.
85-17-02: 85-17-02 MCDONNELL DOUGLAS: Amendment 39-5119. Applies to McDonnell Douglas Model DC-10 and KC-10A airplanes, certificated in any category, which are listed in McDonnell Douglas Service Bulletin 27-195, Revision 1, dated March 25, 1985. Compliance required by May 1, 1988, unless previously accomplished. To minimize the potential operational hazard associated with unnecessary rejected takeoffs caused by slat disagree indications resulting from too narrow tolerances, accomplish the following: \n\n\tA.\tModify the targets and sensors of the outboard slats in accordance with Accomplishment Instructions 2A, 2B, 2D, 2H, 2I, 2J, and 2K contained in McDonnell Douglas DC-10 Service Bulletin 27-195, Revision 1, dated March 25, 1985, or later revisions approved by the Manager, Los Angeles Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\tB.\tAlternate means of compliance which provide an acceptable level of safety may be used when approved by the Manager, Los Angeles 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 in order to comply with the requirements of this AD. \n\n\tAll persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to McDonnell Douglas Corporation, 3855 Lakewood Boulevard, Long Beach, California 90846, Attention: Director, Publications and Training, C1-750 (54-60). These documents also may be examined at the FAA, Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington or the Los Angeles Aircraft Certification Office, 4344 Donald Douglas Drive, Long Beach, California. \n\n\tThis amendment becomes effective September 16, 1985.
62-24-01: 62-24-01 BEECH: Amdt. 508 Part 507 Federal Register November 14, 1962. Applies to All Models 45 (YT-34), A45, B45 (T-34A) and D45 (T-34B) Aircraft With 1,000 Hours or More Total Time In Service. Compliance required within the next ten hours' time in service after the effective date of this AD unless already accomplished within the last 490 hours' time in service and thereafter at intervals not exceeding 500 hours' time in service from the last inspection. Remove both horizontal stabilizers from the aircraft and thoroughly inspect the front and rear spars between the butt rib and the inboard end for cracks, using the dye penetrant method or FAA approved equivalent. If any crack is found in either the spar or reinforcing doubler, replace the stabilizer. NOTE: Operators are requested to send a completed Form FAA 1226 to their local FAA General Aviation District Office if replacement of the stabilizer is required by this AD. (Beech Service Bulletin 45 (YT-34), B45-No. 35, A45 (T-34A) - No. 5, and D45 (T- 34B) - No. 2 covers this same subject.) This directive effective November 26, 1962.
70-25-02: 70-25-02 MCDONNELL DOUGLAS: Amendment 39-1122. DC-8 Airplanes. Applies to airplanes certificated in all categories equipped with Mark II and Mark III anti-skid system installation. \n\n\tCompliance required within the next 50 hours' time in service after effective date of this AD, unless already accomplished. \n\n\tTo prevent misuse of ground spoilers, accomplish the following: \n\n\t(1)\tAdd to Limitations Section of the FAA approved Airplane Flight Manual, the following Ground Spoiler Operation Limitation: DO NOT EXTEND GROUND SPOILERS DURING FLIGHT \n\n\t(2)\tInstall a placard on the pedestal immediately below the word "spoiler" to read: "Deployment in Flight Prohibited, " or an equivalent installation approved by the Chief, Aircraft Engineering Division, FAA Western Region. \n\n\tThis amendment becomes effective December 5, 1970.
2005-13-17: This amendment adopts a new airworthiness directive (AD) for the Agusta S.p.A. (Agusta) Model AB412 Series helicopters. This action requires inspecting each affected tail rotor blade (blade) forward tip weight retention block (tip block) and the aft tip closure (tip closure) for adhesive bond voids, and removing any blade with an excessive void from service. This AD also requires modifying certain blades by installing shear pins and tip closure rivets on all affected blades. This amendment is prompted by reports of in-flight loss of tip blocks and tip closures resulting in minor to substantial damage. The actions specified in this AD are intended to prevent loss of the tip block or tip closure, loss of a blade, and subsequent loss of control of the helicopter.
2005-12-02: The FAA is adopting a new airworthiness directive (AD) to supersede Airworthiness Directive (AD) 98-10-12, which applies to all Revo, Incorporated (REVO) (Type Certificate 1A13 formerly held by Colonial Aircraft Company, Lake Aircraft Corporation, Consolidated Aeronautics, Inc., and Global Amphibians LLC) Models Colonial C-2, Lake LA-4, Lake LA-4A, Lake LA-4P, and Lake LA-4-200 airplanes. AD 98-10-12 currently requires you to ensure adequate clearance between the attachment fitting and the horizontal stabilizer rear beam and between the attachment fitting and the stabilizer skin with inspections, possible replacement, and adjustments as necessary. This new AD is the result of several reports of fatigue cracks found in the horizontal stabilizer attachment fitting (part number 2-2200-21) of Model LA-4-200 airplanes that were in compliance with AD 98-10-12. This includes an airplane accident with a fatality attributed to a fatigue crack in the horizontal stabilizer attachment fitting. Consequently, this AD requires either a dye penetrant inspection of the horizontal stabilizer attachment fitting for any evidence of fretting, cracking, or corrosion (with necessary replacement and modification) or replacement of the fittings depending on the number of operational hours on the fitting. The AD also requires you to repetitively replace the fitting every 850 hours time-in-service (TIS), repetitively inspect (visually) the fittings between replacement times, and report to FAA the results of the initial inspection and any cracks found on repetitive inspections. We are issuing this AD to detect, correct, and prevent future cracks in the horizontal stabilizer attachment fitting, which could result in failure of the horizontal stabilizer attachment fitting. This failure could result in loss of control of the airplane.
2018-07-08: We are adopting a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model A109E, A109K2, A109S, AW109SP, A119, and AW119 MKII helicopters. This AD reduces the life limit of and requires inspecting a tail rotor blade retention bolt (bolt). This AD is prompted by the discovery of a cracked bolt. The actions of this AD are intended to address an unsafe condition on these products.
89-11-03: 89-11-03 BOEING: Amendment 39-6223. \n\tApplicability: Model 737-300 and -400 series airplanes, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\n\tTo prevent the ingestion of "blue ice" into the engine and the potential loss of an engine, accomplish the following: \n\n\tA.\tWithin 200 hours time-in-service after the effective date of this AD: \n\n\t\t1.\tConduct a leak check of the forward lavatory service system, in accordance with Boeing Telex M-7272-89-2127 dated April 25, 1989, and repeat the check at intervals thereafter not to exceed 200 hours time-in-service; or \n\n\t\t2.\tDrain the forward lavatory system, lock the lavatory(s), and placard the lavatory(s) inoperative. \n\n\tB.\tLeaks discovered at any time must be repaired prior to further flight, or the forward lavatory system must be drained, and the lavatory(s) locked and placarded inoperative, prior to further flight. \n\n\tC.\tAn alternate means of compliance or adjustmentof 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\tD.\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 inspections and/or modifications required by this AD. \n\n\tAll persons affected by this directive who have not already received the appropriate service information from the manufacturer may obtain copies upon request to Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington, 98124. This information may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or at the Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, 9010 East Marginal Way South, Seattle, Washington. \n\n\tThis amendment (39-6223, AD 89-11-03) becomes effective on June 5, 1989.
2018-07-06: We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-8 series airplanes. This AD was prompted by a report of restricted movement of the right brake pedals after landing rollout. This AD requires revising the airplane flight manual (AFM) by adding an autobrake system limitation. This AD also requires modifying intercostal webs near a main entry door, which terminates the AFM limitation. We are issuing this AD to address the unsafe condition on these products.
2005-13-15: The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 737-200, -200C, -300, -400, -500, -600, -700, - 700C, -800, and -900 series airplanes. This AD requires a one-time detailed inspection for discrepancies of the secondary fuel vapor barrier of the wing center section, and related investigative/ corrective actions if necessary. This AD is prompted by reports that the secondary fuel vapor barrier was not applied correctly to, or was missing from, certain areas of the wing center section. We are issuing this AD to prevent fuel or fuel vapors from leaking into the cargo or passenger compartments and coming into contact with a possible ignition source, which could result in fire or explosion.
62-23-02: 62-23-02 BELL: Amdt. 498 Part 507 Federal Register October 23, 1962. Applies to Model 47 Series Helicopters Equipped with Main Rotor Mast Thrust Bearing, P/N 47-130-110-1. Compliance required as indicated. Excessive wear and evidence of impending failure of the main rotor mast thrust bearing have occurred. To preclude progression of bearing deterioration to a hazardous degree, accomplish the following: (a) Within the next 25 hours' time in service following the effective date of this AD and thereafter at periods not to exceed 25 hours, conduct a close visual inspection of the engine oil filter. (b) If metal particles are found during any inspection of the engine oil filter, the following shall be accomplished prior to further flight: (1) The source of the contaminant shall be located and eliminated and other components of the engine and transmission which may be jeopardized by metal particles shall be inspected and overhauled as prescribed by the appropriate Bell maintenance manual; and (2) The main rotor mast thrust bearing, P/N 47-130-110-1, shall be thoroughly inspected and replaced with a like component if found not to be in a serviceable condition. (c) Clean engine oil filter carefully before reinstalling. NOTE: For the purpose of this AD, the operations outlined under (a) and (c) are considered to be preventive maintenance and may, therefore, be accomplished by persons specified in Section 18.10(c) of the Civil Air Regulations. This directive effective October 29, 1962. Revised September 16, 1966.
2018-07-12: We are adopting a new airworthiness directive (AD) for all Airbus Model A350-941 airplanes. This AD requires performing repetitive station position pick-off unit (SPPU) calibration tests, and applying the corresponding airplane fault isolation if necessary. This AD was prompted by a report indicating malfunctions of the SPPU and failures of the internal wiring due to water ingress via certain electrical connectors, inducing subsequent icing during flight. We are issuing this AD to address the unsafe condition on these products.
85-12-07: 85-12-07 FOKKER: Amendment 39-5080. Applies to Model F27 series airplanes, serial numbers 10105 through 10648, 10654, 10658 through 10660, 10662 through 10667 and 10669 through 10672, certificated in all categories. To ensure structural integrity of the rudder tab, accomplish the following, unless already accomplished: A. Conduct a one-time visual inspection of the rudder tab in accordance with Fokker Service Bulletin F27/55-58, dated March 28, 1985, within twenty days after the effective date of this AD. B. If incorrect rivets are found, repair the tab before further flight in accordance with the above service bulletin or in a manner approved by the Manager, Seattle Aircraft Certification Office. C. Alternate 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. D. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections and/or modifications required by this AD. All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Fokker B.V., Product Support, P.O. Box 7600, 11172J Schiphol Oost, The Netherlands. These documents also may be examined at FAA Northwest Mountain Region, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington. This amendment becomes effective June 28, 1985.
2005-13-10: The FAA adopts a new airworthiness directive (AD) for certain Cessna Aircraft Company (Cessna) Models 172R, 172S, 182T, T182T, 206H, and T206H airplanes. This AD requires you to inspect any MC01-3A I.C. 9 or MC01-3A I.C. 10 main electrical power junction box circuit breakers for correct amperage (amp) (a correct 40-amp circuit breaker) and replace any incorrect amp circuit breaker with the correct 40-amp circuit breaker. This AD results from several reports of circuit breakers that are not the correct 40-amp circuit breaker installed in the MC01-3A main electrical power junction box. We are issuing this AD to replace any incorrect circuit breaker installed in the MC01-3A I.C. 9 or MC01-3A I.C. 10 main electrical power junction box, which could result in premature tripping of the power junction box main feeder circuit breakers and could lead to partial or complete loss of all electrical power on the airplane. This condition could lead to the loss of all navigation and communication equipment and lighting in the cockpit.
2005-13-09: The FAA adopts a new airworthiness directive (AD) for certain GROB-WERKE Model G120A airplanes. This AD requires you to replace the main landing gear (MLG) up-lock hook assembly. This AD results from mandatory continuing airworthiness information (MCAI) issued by the airworthiness authority for Germany. We are issuing this AD to prevent the MLG from becoming jammed and not extending, which could result in loss of control of the airplane during landing. During the comment period for the notice of proposed rulemaking (NPRM) regarding this action, we received a comment recommending the incorporation of service information to install connecting bolts secured with cotter pins instead of connecting bolts secured with snap rings. All U.S.- registered airplanes currently have these actions incorporated so these actions do not impose an additional burden over that proposed in the NPRM and prior public comment is not necessary. However, we are reopening the comment period to allow the public the chance to comment on these additional actions.
62-19-03: 62-19-03 PIPER: Amdt. 478 Part 507 Federal Register August 23, 1962. Applies to All Model PA-28 Aircraft, Serial Numbers 28-1 to 28-314 Inclusive, 28-317 to 28-326 Inclusive, 28- 328 to 28-331 Inclusive, 28-333 to 28-341 Inclusive, 28-343, 28-345 to 28-348 Inclusive, 28- 351, 28-352, 28-356, 28-359, and 28-365. Compliance required as indicated. There has been inflight failure of the propeller attach bolts due to under-torquing of the bolts. In order to preclude the loss of the propeller due to the failure of the bolts, the following is required: (a) Within the next 10 hours' time in service after the effective date of this AD, unless already accomplished, remove the propeller spinner and remove each propeller attach bolt. (b) Inspect for cracks in the bolt in the area of the threads using magnetic particle or FAA-approved equivalent inspection method in conjunction with a 5-power or higher magnifying glass. Inspect the grip shank for brinelled surfaces with a5-power or higher magnifying glass. (c) If cracks are found or if the bolt is brinelled on the grip shank, replace with new bolts, AN 76-41S. Torque to 300 inch-pounds. (d) If cracks are not found, reinstall the bolts and torque to 300 inch-pounds. (e) In lieu of the inspection requirement of (b), new bolts, AN 76-41S, may be installed and torqued to 300 inch-pounds. (Piper Service Bulletin No. 209, dated April 17, 1962, covers this same subject.) This directive effective August 28, 1962.
2018-07-07: We are adopting a new airworthiness directive (AD) for all Dassault Aviation Model FAN JET FALCON, FAN JET FALCON SERIES D, E, F, and G airplanes; and certain Model MYSTERE-FALCON 20-C5, 20-D5, 20-E5, and 20-F5 airplanes. This AD was prompted by reports of the collapse of the main landing gear (MLG) on touchdown. This AD requires an electrical modification of the landing gear sequence logic. We are issuing this AD to address the unsafe condition on these products.
86-07-11: 86-07-11 BOEING: Amendment 39-5285. Applies to Boeing Model 757 airplanes, line numbers 1 through 90, certificated in any category. Compliance is required within 30 days after the effective date of this amendment. To ensure proper door opening, accomplish the following, unless already accomplished: \n\n\tA.\tInspect the left and right side Number 1, 2, and 4 passenger doors to verify proper engagement of the upper pinch bolt, and reinstall, if necessary, in accordance with Boeing Service Bulletin 757-52A0019, dated February 27, 1986, or later FAA-approved revisions. \n\n\tB.\tAlternate means of compliance or adjustment of 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 inspections and/or modifications required by this AD. \n\n\tAll persons affected by this AD who have not already received copies of the service bulletin cited herein may obtain copies upon request from the Boeing Commercial Airplane Company, P.O. Box 3707, Seattle, Washington 98124. This document 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\tThis amendment becomes effective April 28, 1986.
62-17-04: 62-17-04 EDO: Amendment 473 Part 507 Federal Register August 4, 1962. Applies to Model 249A2870 (A Model Only) Float Installations, Float Serial Numbers 1 to 280, Installed on Cessna Model 180 Series Per STC SA1-622 and Cessna Model 185 Seaplanes. Compliance required within the next 5 hours' time in service after the effective date of this AD, unless already accomplished. Longitudinal cracks have been found on Edo streamlined struts P/N 6061T6, in the area near the 30 and 60 percent chord sections. To preclude operations with defective struts accomplish the following: Visually inspect each side of the full length of the attachment strut, P/N 6061T6, for longitudinal cracks. Replace cracked struts prior to further flight. NOTE: Report the details on any defective struts found to the FAA Engineering and Manufacturing Branch, ATTN: EA-212, Hangar 18, Room 210, New York International Airport, Jamaica 30, New York. (Edo telegram of July 7, and Edo letter ofJuly 9, 1962, cover the same subject.) This directive effective August 14, 1962.
84-23-05: 84-23-05 BOEING: Amendment 39-4949. Applies to Boeing Model 737 series airplanes, certificated in all categories, listed in Boeing Service Bulletin 737-55A1029, Revision 3. To ensure continued structural integrity of the horizontal stabilizer, accomplish the following, unless previously accomplished: \n\n\tA.\tInspect the rear spar horizontal stabilizer attach lugs for cracks in accordance with instructions in Boeing Service Bulletin 737-55A1029, Revision 3, or later FAA approved revision, upon the accumulation of the threshold number of landings specified in Table I of the service bulletin or within 200 landings after the effective date of this AD, whichever occurs later. Repeat these inspections at intervals not exceeding those specified in Table I of the service bulletin. \n\n\tB.\tCracked parts must be replaced or repaired in a manner approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region before further flight. \n\n\tC.\tAirplanes may be flown to a maintenance base for repairs or replacement in accordance with FAR 21.197 and 21.199 with prior approval of the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\tD.\tFor purposes of complying with the AD, subject to the acceptance by the assigned FAA Maintenance Inspector, the number of landings may be determined by dividing each airplane's hours time in service by the operator's fleet average time from takeoff to landing for the airplane type. \n\n\tE.\tAlternate means of compliance which provide an equivalent level of safety may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\tF.\tUpon request by the operator, an FAA Principal Maintenance Inspector, subject to prior approval by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, may adjust the repetitive inspection interval in this AD, if the request contains substantiating data to justify the increase for the operator. \n\n\tAll persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplane Company, P.O. Box 3707, Seattle, Washington 98124. These documents may also be examined at the FAA, Northwest Mountain Region, 9010 East Marginal Way South, Seattle, Washington. \n\n\tThis supersedes Amendment 39-4122 (46 FR 28147; May 26, 1981), AD 81-11-07. \n\tThis Amendment 39-4949 becomes effective December 15, 1984.