AD 98-17-05 SUPERSEDED

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Airbus Model A319, A320, A321, A330, and A340 series airplanes. This action requires revising the Airplane Flight Manual (AFM) to require the flightcrew to discontinue use of any Instrument Landing System (ILS) receiver for which a certain caution message is displayed. This action also requires, for certain airplanes, replacing any faulty ILS receiver with a new, serviceable, or modified unit. This AD also provides for an optional terminating action for the AFM revisions. This amendment is prompted by a pilot's report of errors in the glide slope deviation provided by an ILS receiver. The actions specified in this AD are intended to detect and correct faulty ILS receivers and to ensure that the flightcrew is advised of the potential hazard of performing ILS approaches using a localizer deviation from a faulty ILS receiver, and advised of the procedures necessary to address that hazard.An erroneous localizer deviation could result in a landing outside the lateral boundary of the runway.

Final rule; request for comments.

98-17-05 AIRBUS INDUSTRIE: Amendment 39-10707. Docket 98-NM-154-AD.

Applicability: Model A319, A320, A321, A330, and A340 series airplanes; equipped with AlliedSignal RIA-35B Instrument Landing System (ILS) receivers, part number (P/N) 066-50006-0202; certificated in any category.

NOTE 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.

Compliance: Required as indicated, unless accomplished previously.
To detect and correct faulty ILS receivers and to ensure that the flightcrew is advised of the potential hazard of performing ILS approaches using a localizer deviation from a faulty ILS receiver, and advised of the procedures necessary to address that hazard, accomplish the following:

(a) Within 10 days after the effective date of this AD, accomplish the requirements of paragraphs (a)(1) and (a)(2) of this AD.

(1) 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 into the AFM.

"Instrument Landing (ILS) 1(2) Fault
If 'ILS 1(2) FAULT,' electronic centralized aircraft monitor (ECAM) caution, is triggered at any time during the flight, the affected ILS receiver must be considered as no longer available until it is replaced, and the flight crew must make the appropriate entry in the aircraft maintenance log prior to the next flight.

During an ILS or LOC approach, the glide slope deviation and localizer deviation from ILS receivers 1 and 2 must be monitored and compared. If a discrepancy between the glide slope deviation and/or localizer deviation provided by ILS receivers 1 and 2 is experienced, interrupt the ILS approach.

Do not conduct ILS or LOC approaches using a single ILS receiver.

If ILS 1 has experienced an unannunciated failure there may be late or false ground proximity warning system (GPWS) alerts/callouts. Affected GPWS features may include sink rate alerts, glide slope deviation alerts, and altitude callouts."

(2) Following accomplishment of the AFM revision required by paragraph (a)(1) of this AD, if a caution message reading "ILS 1 FAULT," "ILS 2 FAULT," or "ILS 1+2 FAULT" is displayed intermittently or continuously on ECAM during any portion of any flight: Within 10 days after themessage is first displayed, remove the faulty ILS receiver and install either a new or serviceable part that has the same P/N as the ILS receiver that was removed from the airplane or a part that has been modified in accordance with AlliedSignal Electronic and Avionics Systems Service Bulletin M-4431 (RIA-35B-34-7), Revision 1, dated May 1998.

NOTE 2: The ECAM messages described in paragraph (a)(2) of this AD, when displayed to the pilot, are normally preceded by "NAV" indicating a fault in the navigation system.

(b) Replacement of all RIA-35B ILS receivers, P/N 066-50006-0202, with RIA-35B ILS receivers that have been modified in accordance with AlliedSignal Electronic and Avionics Systems Service Bulletin M-4431 (RIA-35B-34-7), Revision 1, dated May 1998; on which the P/N's have been converted to 066-50006-1202; constitutes terminating action for the requirements of this AD. After the replacement has been accomplished, the limitations required by paragraph (a)(1) may beremoved from the AFM.

NOTE 3: Modification of all AlliedSignal RIA-35B ILS receivers, P/N 066-50006-0202, accomplished prior to the effective date of this AD in accordance with AlliedSignal Electronic and Avionics Systems Service Bulletin M-4431 (RIA-35B-34-7), dated April 1998; is considered acceptable for compliance with the modification specified in this amendment.
(c) As of the effective date of this AD, no person shall install on any airplane an AlliedSignal RIA-35B ILS receiver, P/N 066-50006-0202, that has been found to be discrepant [that is, an ILS receiver for which one of the caution messages specified in paragraph (a)(2) of this AD was displayed on the ECAM] unless the discrepancy has been corrected by modifying the ILS receiver in accordance with AlliedSignal Electronic and Avionics Systems Service Bulletin M-4431 (RIA-35B-34-7), Revision 1, dated May 1998.

(d) 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, International Branch, ANM-116, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Operations Inspector or Principal Avionics Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116.

NOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116.

(e) Special 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.

(f) This amendment becomes effective on August 28, 1998.

The FAA has received a report indicating that, during a test flight of a Boeing airplane, the flightcrew detected discrepancies in the glide slope deviation provided by one of the onboard Instrument Landing System (ILS) receivers. (The glide slope is the vertical flight path that an airplane is to follow when making an ILS landing. The display of the glide slope deviation indicates the position of the airplane relative to the glide slope and indicates to the flightcrew whether the airplane needs to be on a higher or lower glidepath to be on the normal approach flight path.) The discrepancies in the glide slope deviation provided by the discrepant ILS receiver resulted in the display showing that the airplane was on the glide slope, when the airplane was approximately one dot low on the glide slope (as determined from the data provided by the ILS receivers that were operating correctly). The flightcrew received no annunciation that there were discrepancies between the glide slope deviations being provided by the ILS receivers.

An investigation conducted by AlliedSignal, the manufacturer of the RIA-35B ILS receivers installed on the airplane, has revealed that the discrepancies in the glide slope deviation were caused by failure of an internal component of the ILS receiver due to that component's sensitivity to temperature.

The same ILS receiver also provides localizer deviation. (The display of the localizer deviation indicates the position of the airplane relative to the center line of the runway during an ILS landing.) An erroneous localizer deviation could result in a landing outside the lateral boundary of the runway. If a faulty ILS receiver provides a localizer deviation that contains errors that are not detected by the flightcrew, use of a single ILS receiver for ILS or localizer approaches could result in the pilot being directed to land the airplane outside the lateral boundary of the runway. If the localizer deviations generated by two of the ILS receivers onboard the airplane contain errors that are not detected by the flightcrew, during category II and III operations, the autopilot system may land the airplane outside the lateral boundary of the runway.

Additionally, certain ground proximity warning systems (GPWS) and enhanced GPWS's use the glide slope deviation provided by ILS receivers. For these systems, if the ILS receiver used by the GPWS has experienced an unannunciated failure, there may be late or false GPWS alerts/callouts. Affected GPWS features may include sink rate alerts, glide slope deviation alerts, and altitude callouts.

The RIA-35B ILS receivers installed on certain Airbus Model A319, A320, A321, A330, and A340 series airplanes are the same type as those on the affected Boeing airplane. Therefore, those Airbus Model A319, A320, A321, A330, and A340 series airplanes may be subject to the same unsafe condition. Unlike the affected Boeing airplane, during most of the flight profile, the flightcrew on Airbus Model A319, A320, A321, A330, and A340 series airplanes would receive an annunciation of discrepancies between the glide slope or localizer deviations being provided by the ILS receivers. However, such annunciation is not available to the flightcrew during the approach and landing portions of the flight when the ILS is active (ILS tuned and receiving).

Explanation of Relevant Service Information

The FAA has reviewed and approved AlliedSignal Electronic and Avionics Systems Service Bulletin M-4431 (RIA-35B-34-7), Revision 1, dated May 1998, which describes procedures for modifying RIA-35B ILS receivers, part number (P/N) 066-50006-0202. The modification includes removing the radio frequency (RF) assembly; modifying the RF module by cutting two solder-side tracks, installing two 221-ohm resistors, and replacing components U8009 and U8206; and reinstalling the modified RF assembly. Once modified, the P/N of the ILS receiver is converted to P/N 066-50006-1202. Accomplishment of the actions specified in the service bulletin is intended to adequately address the identified unsafe condition.

Airbus has issued A319/320/321 Flight Manual Temporary Revision 4.02.00/03, A330 Flight Manual Temporary Revision 4.02.00/11, and A340 Flight Manual Temporary Revision 4.02.00/22; all dated March 30, 1998. These temporary revisions (TR's) specify that the pilot should discontinue use of an ILS receiver for which a certain caution message ("ILS 1 FAULT," "ILS 2 FAULT," or "ILS 1+2 FAULT") is displayed intermittently or continuously on the electronic centralized aircraft monitor (ECAM) during any portion of the flight, until the affected unit is replaced with a new, serviceable, or modified unit.

U.S. Type Certification of the Airplanes

These airplane models are manufactured in France and are type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement.

Explanation of Requirements of Rule

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD is being issued to detect and correct faulty ILS receivers and to ensure that the flightcrew is advised of the potential hazard of performing ILS approaches using a localizer deviation from a faulty ILS receiver, and advised of the procedures necessary to address that hazard. This AD requires a revision to the Limitations Section of the FAA-approved Airplane Flight Manual (AFM) to provide the flightcrew with explicit restrictions on operation in the event that a certain caution message is displayed intermittently or continuously on the ECAM during any portion of the flight. For cases where certain caution messages are displayed, this AD also requires replacement of the faulty ILS receiver with a new, serviceable, or modified unit. ThisAD also provides for an optional terminating action for the AFM revision described previously.

Explanation of the Applicability of the Rule

The FAA notes that its general policy is that, when an unsafe condition results from the installation of an appliance or other item that is installed in a limited number of airplane models, an AD is issued so that it is applicable to those airplanes, rather than the item. The reason for this is simple: making the AD applicable to the airplane models on which the item is installed ensures that operators of those airplanes will be notified directly of the unsafe condition and the action required to correct it. While it is assumed that an operator will know the models of airplanes that it operates, there is a potential that the operator will not know or be aware of specific items that are installed on its airplanes. Therefore, calling out the airplane model as the subject of the AD prevents "unknowing non-compliance" on the part of the operator.

Interim Action

This is considered to be interim action. The FAA is considering further rulemaking action to require replacement of all existing RIA-35B ILS receivers with modified parts, which would constitute terminating action for the AFM revision required by this AD action. However, the planned compliance time for such replacement is sufficiently long so that notice and opportunity for prior public comment will be practicable.

Differences Between the Rule and the Airbus Temporary AFM Revisions

The FAA is not referencing the Airbus TR's described previously as the appropriate source of service information.

Operators should note that, unlike the procedures described in the TR's, this AD would not permit use of a single ILS receiver for ILS or localizer approaches. The TR's allow use of a single source ILS receiver for ILS or localizer approaches even though the ILS receiver does not display caution messages on the ECAM during the approach and landingportions of the flight when the ILS is active. If there is a failure of a single ILS, or if the aircraft is dispatched with a single operative ILS, there is no way for the crew to identify a failure of the second ILS during these phases of flight. In such a case, the remaining ILS receiver may be providing erroneous localizer or glide slope deviation, and, therefore, a single ILS receiver should not be used for ILS or localizer approaches.

Operators also should note that, unlike the procedures described in the TR's, this AD would not permit an ILS approach to be continued if a discrepancy between the glide slope and/or localizer deviation provided by ILS receivers 1 and 2 is detected. The TR's allow the crew to continue the ILS or localizer approach, if the crew can immediately identify the faulty ILS. This determination is to be made by the crew, based on continuous monitoring and comparison of the glide slope and localizer deviations displayed from both ILS receivers. However, should a discrepancy be detected during this continuous monitoring and comparison procedure, it may not be apparent to the crew which ILS receiver is providing correct glide slope and/or localizer deviation. For this reason, during an ILS or localizer approach, if the crew detects a discrepancy between the glide slope and/or localizer deviation provided by the two ILS receivers, the ILS approach should be immediately interrupted.

Determination of Rule's Effective Date

Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited

Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption "ADDRESSES." All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.

Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.

Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 98-NM-154-AD." The postcard will be date stamped and returned to the commenter.

Regulatory Impact

The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.

The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft,and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption "ADDRESSES."

List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: PART 39 - AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. 39.13 [Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive:

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane
Directorate, ANM-114, Attention: Rules Docket No. 98-NM-154-AD, 1601 Lind Avenue, SW., Renton,
Washington 98055-4056.
The service information referenced in this AD may be obtained from AlliedSignal Aerospace, Technical
Publications, Dept. 65-70, P.O. Box 52170, Phoenix, Arizona 85072-2170. This information may be examined
at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington.

Tim Backman, Aerospace Engineer, International Branch,
ANM-116, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056;
telephone (425) 227-2797; fax (425) 227-1149.