Results
2012-15-16: We are adopting a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8 series airplanes. This AD was prompted by reports that various pushrods had been manufactured with tubes having the incorrect heat treatment. This AD requires replacing the affected pushrod assembly. We are issuing this AD to prevent loss of rudder control, reduced directional control of the airplane on the ground, or a jammed nose landing gear (NLG) door that could prevent the NLG from retracting or extending.
92-18-02: 92-18-02 BRITISH AEROSPACE: Amendment 39-8346. Docket No. 92-NM-49-AD. Applicability: Model ATP series airplanes; serial numbers 2001 through 2045, inclusive; certificated in any category. Compliance: Required as indicated, unless accomplished previously. To prevent loss (shut-down) of electronic flight instruments system (EFIS) displays, accomplish the following: (a) Within 180 days after the effective date of this AD, install fixed fittings, Modification 10248C, and filter units, Modification 10248A, in the electrical power supplies to the main and side windscreen heater system at the rear of the EFIS control panel, in accordance with British Aerospace Service Bulletin ATP-30-20-10248A/-10248C, Revision 1, dated February 17, 1992. (b) An 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, Standardization Branch, ANM-113, 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, Standardization Branch. NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch. (c) Special 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. (d) The installation shall be done in accordance with British Aerospace Service Bulletin ATP-30-20-10248A/-10248C, Revision 1, dated February 17, 1992, which contains the following list of effective pages: Page Number Revision Level Date 1-27, 1 February 17, 1992 Odd pages 29 to 97, 99-103 Even pages 28 to 98 (Not used) 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 British Aerospace, PLC, Librarian for Service Bulletins, P.O. Box 17414, Dulles International Airport, Washington, DC. 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. (e) This amendment becomes effective on November 20, 1992.
98-06-27: This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 Mark 0100 series airplanes, that requires installation of additional "EXIT" signs at the overwing emergency exits. This amendment is prompted by a report indicating that the "EXIT" signs for the overwing emergency exits, as currently installed, would not be visible to passengers during an emergency evacuation when the emergency exit doors are open. The actions specified by this AD are intended to ensure the "EXIT" signs for overwing emergency exits are clearly visible during an evacuation.
82-15-05: 82-15-05 LOCKHEED-CALIFORNIA COMPANY: Amendment 39-4420. Applies to Lockheed-California Company Model L-1011 Series airplanes, certificated in all categories. Compliance required within six months from the effective date of this AD, unless already accomplished for items B and C, and within twelve months for item A. To prevent APU electrical power supply cable arcing resulting from chafing or abrasion, accomplish the following: A. Install wire harness shield per Part 2 of Lockheed-California Company L-1011 Service Bulletin 093-25-254 dated October 25, 1976, or later revisions approved by the Chief, Los Angeles Area Aircraft Certification Office, FAA Northwest Mountain Region. B. Perform a one-time inspection of the APU feeder cable harness J130 for clearance from stringer No. 42, and install a cable harness support if found necessary in accordance with Part 2 of Lockheed-California Company L-1011 Service Bulletin 093-53-182 dated June 18, 1980, or later revisions approved by the Chief, Los Angeles Area Aircraft Certification Office, FAA Northwest Mountain Region. C. Perform a one-time inspection of each APU feeder cable harness No. J130 and harness No. X043, and install wire harness support(s) if found necessary in accordance with Part 2 of Lockheed-California Company L-1011 Service Bulletin 093-24-097 dated November 20, 1980, or revision 1 dated July 31, 1981, or later revisions approved by the Chief, Los Angeles Area 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 in order to comply with the requirements of this AD. E. Alternate means of compliance which provide an equivalent level of safety may be used when approved by the Chief, Los Angeles Area Aircraft Certification Office, FAA Northwest Mountain Region. The manufacturer's specifications and procedures identified and described in this directive areincorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Lockheed-California Company, P.O. Box 551, Burbank, California 91520, Attention: Commercial Support Contracts, Dept. 63-11, U-33, B-1. These documents also may be examined at FAA Northwest Mountain Region, 17900 Pacific Highway South, C-68966, Seattle, Washington 98168; or Los Angeles Area Aircraft Certification Office, 4344 Donald Douglas Drive, Long Beach, California 90808. This amendment becomes effective August 27, 1982.
2012-15-17: We are adopting a new airworthiness directive (AD) for all Airbus Model A300 B4-603, B4-605R, and B4-622R airplanes; Model A300 C4-605R Variant F airplanes; and Model A300 F4-600R series airplanes. This AD was prompted by a report that chafing was detected between the autopilot electrical wiring conduit and the wing bottom skin. This AD requires modifying the wiring installation on the right-hand wing. We are issuing this AD to prevent sparking due to electrical chafing when flammable vapors are present in the area, which could cause an uncontrolled fire. [[Page 47274]]
2009-04-09: We are superseding an existing airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) issued by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: There have been reports of inter-rivet cracking on several wing front spar adapter assemblies (P/N C6WM1027-1) on the horizontal and vertical flanges. It was determined that the cracking was caused by stress corrosion in the short transverse grain initiated by local riveting induced stresses. We are issuing this AD to require actions to correct the unsafe condition on these products.
98-06-39: This amendment adopts a new airworthiness directive (AD) that is applicable to Eurocopter France Model AS 332C, L, L1, and L2 helicopters. This action requires determining the thickness of the shim washers, inspecting certain cockpit door hinge tenons (hinge tenons) for cracks, and if a crack is found, replacing the hinge tenon with an airworthy hinge tenon. This amendment is prompted by several reports of cracked hinge tenons due to improper shimming. The actions specified in this AD are intended to detect cracks in the hinge tenons due to unintended loading of the improperly shimmed tenons caused by closing the door, which may lead to separation of the door from the helicopter, impact with the main rotor or tail rotor system, and subsequent loss of control of the helicopter.
78-11-06: 78-11-06 BEECH: Amendment 39-3226. Applies to Model 65-A90, B90 and C90 (Serial Numbers LJ-114 through LJ-705), and Model E90 (Serial Numbers LW-1 through LW-141) airplanes incorporating Beechcraft H-14 autopilot installations with a 13.5 inch diameter elevator servo bellcrank. To preclude possible failure of the elevator control cable, unless already accomplished. A) Before the next flight, except for those airplanes previously modified in accordance with Beech Modification Kit Number 90-9067-1S, open the aft fuselage belly access door and locate the autopilot elevator servo bellcrank at F.S. 319.00, located to the left of centerline. Measure the bellcrank and if it measures 10 inches or less no further action is required. If the bellcrank measures 13.5 inches or larger (groove to groove), visually inspect the primary elevator control cable, the pulley bracket at F.S. 340.00, the autopilot servo cable, and autopilot bellcrank in accordance with Beech Service Instructions No. 0988, or later approved revisions. If there is no evidence of cable rubbing or damage to the airplane, no further immediate action is required. 1. If rubbing of the elevator cable is noted, but no damage has occurred. a. Disconnect and remove the autopilot servo cable from the airplane. b. Install a locally fabricated placard in plain view of the pilot indicating "AUTOPILOT INOPERATIVE". 2. If fraying of the elevator cable or other damage is noted: a. Replace the elevator cable and repair or replace any other damaged parts. b. Accomplish paragraphs A)1.a. and 1.b. B) If not previously accomplished, on or before September 1, 1978, modify the servo mount of any Beechcraft H-14 elevator autopilot servo having a 13.5 inch diameter or larger bellcrank in accordance with Beech Modification Kit Number 90-9067-1S, or later approved revisions. Upon the completion of this modification any autopilot made inoperative under paragraphs A)1. orA)2. of this AD may be returned to service and the "AUTOPILOT INOPERATIVE" placard removed. C) Aircraft may be flown in accordance with 21.197 to a base where the inspection required by this AD can be accomplished, after coordination with the Chief, Engineering and Manufacturing Branch, FAA, Central Region. D) Any equivalent method of compliance with this AD must be approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region. This amendment becomes effective June 8, 1978, to all persons except those to whom it has already been made effective by air mail letter from the FAA dated May 4, 1978.
2011-19-01 R1: We are revising an existing airworthiness directive (AD) that applies to all Airbus Model A318, A319, A320, and A321 series airplanes. The existing AD currently requires revising the airplane flight manual (AFM) to include a procedure intended to address the unsafe condition, an inspection of the firewall connector for signs of arcing if an integrated drive generator (IDG) (or generator (GEN)) was shut down in-flight automatically or using the AFM procedure, and corrective action if necessary; and provides an optional terminating action for certain AFM revision and inspections. This AD was prompted by the potential for an inadvertent error by flightcrew to use the IDG switch instead of the GEN switch when doing the AFM display unit failure procedure required by the existing AD. This AD retains the actions required by the existing AD and clarifies certain terminology. We are issuing this AD to prevent transient loss of certain systems, which could result in the reduced abilityof the flightcrew to cope with adverse flight conditions.
2006-23-05: The FAA is adopting a new airworthiness directive (AD) for all Cessna Model 750 airplanes. This AD requires inspecting the inboard- hinge brackets of the left and right elevators for cracking, and doing related investigative and corrective actions if necessary. This AD results from a report of cracking found on the elevator inboard-hinge brackets. We are issuing this AD to detect and correct cracking of the elevator inboard-hinge brackets, which could result in structural failure of the elevators and consequent loss of control of the airplane.
77-08-07: 77-08-07 MESSERSCHMITT-BOLKOW-BLOHM (MBB): Amendment 39-2880. Applies to Model BO-105A and BO-105C helicopters, serial numbers S101 through S200, certificated in all categories, that incorporate external load hook assembly P/N 105-80322. Compliance is required as indicated, unless already accomplished. To prevent the possible inability to release an external load, accomplish the following: (a) Within the next 5 hours time in service after the effective date of this AD, either - (1) Install an operating limitation placard on the instrument panel in full view of the pilot, setting forth the following limitation "EXTERNAL LOAD OPERATIONS PROHIBITED"; or (2) Replace wire bundle 22VB, P/N 105-98327, with new bundle, P/N 105- 98326, and change the wiring connection of the associated connector plug 5MDA in accordance with subparagraph 2B of MBB Service Bulletin No. 80-21, dated July 25, 1975, or equivalent approved by the Chief, Aircraft Certification Staff, FAA, Europe, Africa, and Middle East Region, c/o American Embassy, A.P.O. New York, N.Y. 09667. (b) The operating limitation placard required by paragraph (a)(1) of this AD may be removed upon compliance with paragraph (a)(2) of this AD. This amendment becomes effective May 6, 1977.
98-06-26: This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 Mark 0100 series airplanes, that requires repetitive inspections to detect corrosion in the wheel axles of the main landing gear (MLG) sliding members; and rework of any corroded areas, an inspection to detect cracks in the wheel axles, and replacement of any cracked sliding member. This AD provides for interim actions that may be accomplished in lieu of the repetitive inspections. This AD also requires eventual modifications of the main wheel brake units and the MLG sliding members; when accomplished, these modifications terminate the repetitive inspections and interim actions. This amendment is prompted by a report of failure of an MLG wheel axle during push back of an in-service airplane from the terminal. The actions specified by this AD are intended to prevent failure of the MLG wheel axle due to problems associated with corrosion and cracking.
81-06-06: 81-06-06 BRITISH AEROSPACE: Amendment 39-4065. Applies to Model HS/DH/BH- 125 airplanes series -3A/R, -3A/RA, and -3A/RA with British Aerospace Modification 25/2600 installed; series -400A and -400A with British Aerospace Modification 25/2550 or STC SA3870WE installed; and series -600A and -600A with British Aerospace Modification 25/2468 installed, certificated in all categories. Compliance is required as indicated, unless already accomplished. To prevent restricted movement of the flap control unit input lever and chafing of the left engine fuel line due to possible interferences, accomplish the following: (a) Within 50 hours time in service after the effective date of this AD, inspect: (1) For chafing of the left engine fuel feed line; and (2) For recommended clearance between the fuel feed line and the flap control unit input lever in accordance with paragraph 2A(1), (2), and (3) of the Accomplishment Instructions of British Aerospace Service Bulletin28-69, Revision 1, dated June 25, 1979 (hereinafter referred to as the service bulletin) or an equivalent approved by the Chief, Aircraft Certification Staff, Federal Aviation Administration, Europe, Africa, and Middle East Office, Brussels, Belgium. (b) If as a result of the inspections required in paragraph (a) of this AD - (1) Chafing or other damage to the fuel line is found, before further flight, except that aircraft may be flown in accordance with FAR Section 21.197 to a base where the work can be performed, replace the fuel line with a serviceable fuel line of the same P/N. (2) Clearance between the engine fuel feed line and the flap control unit input lever is found to be less than 0.15 inches, before further flight, increase the clearance in accordance with paragraph 2A(4) of the service bulletin. (c) Upon completion of the actions required in paragraphs (a) and (b) of this AD, return the aircraft to service in accordance with paragraphs 2A(5) and 2A(6)of the service bulletin. This amendment becomes effective March 26, 1981.
2012-15-10: We are adopting a new airworthiness directive (AD) for certain The Boeing Company Model 747-400 and 747-400D series airplanes. This AD was prompted by a report of an in-flight multi-power system loss of the 1, 2, and 3 alternating current electrical power systems located in the main equipment center (MEC). This AD requires installing aluminum gutter reinforcing brackets to the forward and aft drip shield gutters of the MEC; and adding a reinforcing fiberglass overcoat to the top surface of the MEC drip shield, including an inspection for cracking and holes in the MEC drip shield, and corrective actions if necessary. This AD also provides for an option to install an MEC drip shield drain system, which, if accomplished, would extend the compliance time for adding the reinforcing fiberglass overcoat to the top surface of the MEC drip shield. We are issuing this AD to prevent water penetration into the MEC, which could result in the loss of flight critical systems.
2010-10-18: We are adopting a new airworthiness directive (AD) for the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: Investigation of a recent high altitude loss of cabin pressurization on a BD-100-1A10 aircraft determined that it was caused by a partial blockage of a safety valve cabin pressure- sensing port, in conjunction with a dormant failure/leakage of the safety valve manometric capsule. The blockage, caused by accumulation of lint/dust on the grid of the port plug, did not allow sufficient airflow through the cabin pressure-sensing port to compensate for the rate of leakage from the manometric capsule, resulting in the opening of the safety valve. It was also determined that failure of the manometric capsule alone would not result in the opening of the safety valve. * * * * * The unsafe condition is possible loss of cabin pressure caused by the opening of the safety valve. This AD requires actions that are intended to address the unsafe condition described in the MCAI.
2012-15-11: We are adopting a new airworthiness directive (AD) for certain Dassault Aviation Model FALCON 7X airplanes. This AD was prompted by a report that a passenger oxygen pipe at frame 10 was chafing against the forward lavatory rear structure, raising the risk of the oxygen pipe developing a crack. This AD requires modifying the routing of and, if necessary, replacing, the oxygen pipe. We are issuing this AD to prevent rupture of the oxygen pipe which, in case of a cabin depressurization, would impair operation of the passenger oxygen distribution system.
98-06-30: This amendment supersedes an existing airworthiness directive (AD), applicable to certain Raytheon (Beech) Model 400, 400A, 400T, MU-300, MU-300-10 airplanes, that currently requires replacement of outflow/safety valves with serviceable valves. This amendment revises the applicability of the existing AD to add an airplane model and to remove other airplanes, as well as to identify the serial numbers of affected airplanes. The actions specified by this AD are intended to prevent cracking and consequent failure of the outflow/safety valves, which could result in rapid decompression of the airplane.
90-02-07: 90-02-07 AEROSPATIALE: Amendment 39-6466. Docket No. 89-NM-266-AD. Applicability: Model ATR42 series airplanes, Serial Numbers 003 through 100, certificated in any category. Compliance: Required within 30 days after the effective date of this AD, unless previously accomplished; and thereafter, compliance is required immediately following any maintenance action which could result in mis-wiring and/or mis-plumbing. To detect incorrectly installed fire protection system plumbing and/or wiring, accomplish the following: A. Conduct an inspection of the right engine fire extinguishing system wiring and plumbing in accordance with the Aerospatiale All Operators Information Message DS/E 20/89, dated December 4, 1989. If any pipes or electrical connectors are improperly installed, prior to further flight, correct the installation in accordance with the Aerospatiale message. B. An alternate means of compliance or adjustment of the compliance time, which providesan acceptable level of safety, may be used when approved by the Manager, Standardization Branch, ANM-113, FAA, Northwest Mountain Region. NOTE: 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, Standardization Branch, ANM-113. C. Special 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. All persons affected by this directive who have not already received the appropriate service information from the manufacturer may obtain copies upon request to Aerospatiale, 316 Route de Bayonne, 31060 Toulouse Cedex 03, France. This information may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or the Standardization Branch, 9010 East Marginal Way South, Seattle, Washington. This amendment (39-6466, AD 90-02-07) becomes effective on January 23, 1990.
89-21-06: 89-21-06 BRITISH AEROSPACE: Amendment 39-6346. Docket No. 89-NM-87-AD. Applicability: Model BAe 125-800A series airplanes equipped with Grumman Aerospace Corporation engine exhaust duct Part No. C46P13100-3 or C46P13100-103 (not applicable to airplanes with Dee Howard thrust reversers) certificated in any category. Compliance: Required within 180 days after the effective date of this AD, unless previously accomplished. To prevent collapse of the engine exhaust duct, accomplish the following: A. Replace the left and right engine exhaust ducts in accordance with British Aerospace Service Bulletin 71-40-3213A, Revision 2, dated April 12, 1989. B. An 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, Standardization Branch, ANM-113, FAA, Northwest Mountain Region. NOTE: 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, Standardization Branch, ANM-113. C. Special 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. All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to British Aerospace, PLC, Service Bulletin Librarian, P.O. Box 17414, Dulles International Airport, Washington, D.C. 20041. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or the Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington. This amendment (39-6346, AD 89-21-06) becomes effective on November 8, 1989.
2012-15-09: We are adopting a new airworthiness directive (AD) certain Airbus Model A310-203, -221, and -222 airplanes. This AD was prompted by the manufacturer re-classifying slat extension eccentric bolts as principal structural elements with replacement due at or before their calculated fatigue lives. This AD replaces certain slat extension eccentric bolts with new bolts. We are issuing this AD to prevent fatigue cracking, which could result in the loss of structural integrity of the airplane.
98-06-23: This amendment adopts a new airworthiness directive (AD), applicable to certain Saab Model SAAB 2000 series airplanes, that requires application of sealant to the auxiliary power unit (APU) firezone bulkhead. This amendment is prompted by issuance of mandatory continued airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent hazardous amounts of flame, fuel, and vapor from entering compartments outside the fire zone due to unsealed openings in the firezone bulkhead, which could result in a fire outside the APU firezone compartment.
2012-15-03: We are adopting a new airworthiness directive (AD) for all Embraer S.A. Model ERJ 190 airplanes. This AD was prompted by a report of damage on the rod end of the retracting actuator rod of the main landing gear (MLG). This AD requires performing a one-time general visual inspection to determine if a certain part number is installed on the MLG retraction actuator; if necessary, performing a general visual inspection for discrepancies between the actuator rod end and shock strut lug of the MLG retraction actuator; and corrective actions if necessary. We are issuing this AD to detect and correct breakage of the MLG retracting actuator rod, which may result in MLG extension with no hydraulic damping and consequent damage to the locking mechanism and collapse of the MLG.
2012-14-12: We are adopting a new airworthiness directive (AD) for Arrow Falcon Exporters, Inc. (previously Utah State University); Firefly Aviation Helicopter Services (previously Erickson Air-Crane Co.); California Department of Forestry; Garlick Helicopters, Inc.; Global Helicopter Technology, Inc.; Hagglund Helicopters, LLC (previously Western International Aviation, Inc.); International Helicopters, Inc.; Precision Helicopters, LLC; Robinson Air Crane, Inc.; San Joaquin Helicopters (previously Hawkins and Powers Aviation, Inc.); S.M.&T. Aircraft (previously US Helicopters, Inc., UNC Helicopter, Inc., Southern Aero Corporation, and Wilco Aviation); Smith Helicopters; Southern Helicopter, Inc.; Southwest Florida Aviation International, Inc. (previously Jamie R. Hill and Southwest Florida Aviation); Tamarack Helicopters, Inc. (previously Ranger Helicopter Services, Inc.); US Helicopter, Inc. (previously UNC Helicopter, Inc.); West Coast Fabrication; and Williams Helicopter Corporation (previously Scott Paper Co.) Model HH-1K, TH-1F, TH-1L, UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and UH-1P Helicopters; and Southwest Florida Aviation Model UH-1B (SW204 and SW204HP) and UH-1H (SW205) Helicopters. This AD requires [[Page 44435]] 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. This AD was prompted by reports of missing tip blocks or tip closures, resulting in minor to substantial damage to blades installed on Bell Model 212 and 412 helicopters. The actions are intended to prevent loss of a tip block or tip closure, loss of a blade, and subsequent loss of control of the helicopter.
98-06-06: This amendment adopts a new airworthiness directive (AD) that is applicable to GKN Westland Helicopters Ltd. (Westland) 30 series helicopters. This action requires determining the total hours time-in-service (TIS) of the six tail rotor drive shafts (drive shafts), creating a component history card or an equivalent record for each shaft, and replacing those drive shafts that exceed a certain TIS with an airworthy drive shaft. This amendment is prompted by findings of drive shaft attachment flange cracks on similar British military model helicopters. This condition, if not corrected, could result in failure of the drive shaft coupling attachment flanges that could result in loss of power to the tail rotor and subsequent loss of control of the helicopter.
98-06-15: This amendment adopts a new airworthiness directive (AD), applicable to certain Fokker Model F28 Mark 0100 series airplanes, that requires replacement of the return filter diaphragm assemblies on hydraulic systems 1 and 2 with modified filter units having new diaphragms. This amendment is prompted by a report of insufficient running clearance of the brake units due to overpressure in the hydraulic return system; this condition could lead to brake overheating. The actions specified by this AD are intended to prevent too high pressure in the hydraulic return system during the selection of subsystem(s), which could result in inadvertent braking and/or blown tires.