Kent V. Hollinger, Chair
Aging Transport Systems Rulemaking Advisory Committee

I first became involved in the "Aging Systems" issue in March 1998 while employed as Chief Engineer at Northwest Airlines. Boeing held a meeting at the end of that month to brief the airlines on the results of the aircraft inspections which they had accomplished together with FAA inspectors. The intent of the aircraft inspections was to obtain first-hand information on the state of aged systems, as recommended by the White House Commission on Aviation Safety and Security (Gore Commission). Further aircraft inspections were planned over the next month.

A follow-on meeting was held in mid-April which included FAA representatives who were seeking industry input prior to formulating an aging systems plan. The team agreed that the top four potential aging system concerns were wiring, connectors, grounds and circuit breakers.

Later that same month, Michael Rioux, Vice President of Engineering, Maintenance & Material for the Air Transport Association, wrote a letter to Mr. Gregory Dunn of the FAA which outlined several points for consideration in the final aging systems plan as well as three voluntary initiatives proposed by the airlines:

1. All operators will enhance their FAA-approved maintenance programs to include systems inspections based upon philosophy similar to the logic contained in MSG-3 analysis.
2. ATA member airlines will volunteer to participate in FAA-sponsored forums to improve the format of reporting for ease of data analysis.
3. ATA member airlines and Boeing will voluntarily commit to undertake a review of previous Service Bulletins to identify aging related systems safety improvements for future incorporation on DC-8, DC-9, DC-10, B727, B737-100/200 and B747-100/200/300 aircraft models. (NOTE: A300 and L-1011 aircraft were subsequently added to this list).

In June, industry and FAA held an additional meeting to develop short-term actions which would complement the long-term FAA plan which would be published soon. It was agreed at that time to form an Aging Systems Task Force, comprised of a lead airline representative from each of the fleet types that were over 20 years old, the airframe manufacturers and the FAA. I was asked to chair this effort. Seven aircraft model specific Task Force Working Groups were formed to develop detailed plans for each fleet type. It was also agreed that airlines and manufacturers would share "best practices" concerning maintenance of aircraft systems.

The Aging Systems Task Force (ASTF) met again on July 14, 1998, to develop detailed guidelines for use by each of the Working Groups. Also, a smaller project team was assigned to work with Kristin Larson of the FAA to consolidate the supplied "best practices" into a single document. This effort resulted in the publishing of ATA Spec 117: Wiring Maintenance Practices/Guidelines on July 31, 1998. An accompanying instructional video was also created to improve information dissemination and training.

The FAA Aging Transport Non-Structural Systems Plan, dated July 1998, was issued in late summer. The "Blue Book" defined seven long-term tasks for further action, as well as the results of the initial aircraft inspections.

On October 1, 1998, the FAA Administrator announced a new plan to enhance the safety of aging aircraft systems. In this plan, the work of the ASTF was to be expanded to include several other initiatives. An advisory committee (which became ATSRAC) was announced to oversee much of this work and I was named as chair. Once the official order was issued, the first meeting of ATSRAC was held January 20, 1999.

Meanwhile, the ASTF was continuing upon its mission. The group met on November 3-4, 1998, to review the progress of its Working Groups. By that time detailed inspection instructions had been developed for each aircraft model, and both a B727 and B747 had already been inspected.

At the January 1999 ATSRAC meeting, the committee voted to form Working Groups to perform the detailed work on its taskings. Due to the significant amount of progress already made by the ASTF, it was decided by ATSRAC to create Working Group #1 by expanding the membership of the existing ASTF to include several ATSRAC members, as well as Mr. Edward Block. This Working Group was then assigned the work involved with ATSRAC Tasks #1 and #2. Three other Working Groups were established to accomplish the remaining three tasks.

The following schematic organizational chart shows the four Working Groups established by ATSRAC, along with the existing eight ASTF Working Groups:

The Working Groups involved with Maintenance Criteria, Training and Manuals will present their recommendations to ATSRAC at our October 2000 meeting. Since the ASTF has issued a final report (dated August 1, 2000) which has been approved by ATSRAC, I will limit my remaining testimony at this time to the efforts contained in that report.

The direction given to ASTF was that their main focus should be on aircraft wiring and electrical systems. In general it was agreed that other aircraft systems (such as hydraulics, pneumatics, oxygen, flight controls, etc.) are monitored by ever evolving maintenance programs. However, the electrical systems were not specifically reported or monitored for reliability purposes.

The three primary tasks assigned to ASTF were:

1. Conduct an in-depth survey of the condition of aging transport airplane fleet systems and propose model-specific safety recommendations related to airplane systems that will eliminate or significantly reduce hazards associated with the types of age-related degradation displayed by the fleet.
2. Review service history, manufacturer's service bulletins, manufacturer's service letters, and applicable Airworthiness Directives for the aging transport fleet. Identify information which pertains to aging systems for possible mandatory action.
3. Review any Airworthiness Directives that require repetitive inspections, and determine if continued inspections are warranted, or if a terminating action is appropriate.

After first reviewing the membership of ASTF, I will describe the processes, findings, and recommendations of the Task Force.

ASTF Participation

The task force obtained support from both domestic and foreign operators and from both passenger and cargo airlines. The diversity of their size, operations, fleet makeup, and maintenance practices provided a well-rounded view of aging transport systems. The airline representatives were primarily from the maintenance and engineering departments.

The FAA participation included representatives from the Flight Standards and Certification Branches, from the Northwest Mountain and Southern Regions, and from FAA headquarters.

All three airframe manufacturers (Airbus, Boeing and Lockheed) were involved in the formation of the ASTF. Other participants included wiring and tooling manufacturers, the Air Force, the Navy, the ATA, the International Aviation Safety Association, the SAE, and others. Therefore, participation in the task force included experienced representatives from organizations which encompass all aspects of the industry. Those participating are, in effect, industry experts on airplane wiring on commercial and military airplanes.

Aircraft Survey Inspections

The first task was to survey the condition of the wiring systems of older in-service airplanes. At ATSRAC direction, ASTF targeted airplanes which were greater than twenty years old.

As shown on the organizational chart, a separate Working Group was created for each of the eight aircraft model types. The Working Groups developed specific inspection procedures unique to each model, but with a format common across all models. These procedures normally were formatted like an OEM Service Bulletin. The inspections focused primarily on harsh environmental areas (such as wheel wells, under lavatories and high heat areas), areas with high maintenance activity and heavy traffic areas. Standard forms were created to emphasize and document various types of findings. Findings were categorized by defects found in four types of hardware; wiring, connectors, terminations and installations.

The Working Groups either conducted the surveys themselves or commissioned teams of airline personnel to perform them. After inspecting 81 aircraft, the findings consisted of 3,215 non-routine items, all of which required some action on the part of the operator to address the condition before the aircraft re-entered service. Identification of non-routine items during heavy maintenance is not atypical. The sequencing of the wiring survey within the normal aircraft assessment conducted upon entry into heavy maintenance influenced the findings. Some of the wiring items were found as a result of the non-intrusive survey whereas others were found during the normal receiving assessment.

The definitions below were used to categorize the findings.

Immediate Fleetwide Safety of Flight Concern

• A discrepancy or safety of flight concern requiring immediate fleet action. Impending critical failure seen in the sample.
  
• Items found - 0

Potential Hazard or Frequently Occurring (Significant) Item

• A defect, which may require design changes or notification for enhanced inspection based on
• potential hazard (e.g. fire, bundle damage, essential system damage
  
• frequency of occurrence at a specific location
• Items found - 182

Defects Noted

• A minor discrepancy not requiring any fleet action.
  
• Items found - 3033

When the Working Groups looked at these 3,215 items, they determined that based on the resulting potential hazard or the frequency of findings in a specific area, 182 of them were deemed significant enough to warrant additional evaluation. An example of a significant item that may warrant further action is a wire bundle routed close to structure when the routing problem was noted on more than one airplane under survey. None of the 3,215 items were found to be obvious and immediate fleetwide safety of flight concerns.

Due to schedule and data availability constraints on the task force, the OEMs were requested to conduct detailed reviews of the significant items found during the non-intrusive wiring survey. Their reviews were conducted using the same existing processes used by their customer engineers for technical issues. The OEM review process and the format of the results were presented to and agreed upon by the ASTF.

Finally, the results of the OEM review were provided to the model specific Working Groups for review. The results were amended and/or approved by these groups prior to publication. This activity was completed in the spring of 2000.

Summary of Non-Intrusive Aircraft Survey Findings
A/C Type	DC8	DC9	DC10	727	737	747	A300	L1011
No. of A/C Inspected	14	15	14	9	9	7	10	3
Age Range	29-31	20-32	12-27	17-33	18-22	15-24	10-17	18-26
Immediate Fleetwide Safety	0	0	0	0	0	0	0	0
Significant Items	10	10	62	62	3	3	5	27
Total Items	974	116	714	276	399	238	408	247
Items Per A/C	70	8	51	31	26	34	42	83
Avg Manhour per a/c	N/A	8 per SB	67 actual	40 per SB	40 per SB	Not Avail	Not Avail	40 per SB
Inspection By:	Insp	Mech	Mech	Mech	Insp	WG	OEM Eng'r	WG or Mech
Inspection Location:	hmv	hmv	hmv	hmv	hmv	hmv	hmv or p-f	retired or hmv
		p - f - passenger to frt'r conversion hmv – heavy maintenance visit

The ASTF survey of wiring resulted in a validation of the existing procedures used by industry to continuously identify and correct wiring problems throughout the life of an airplane. Although these procedures cannot always prevent an actual or potential wiring problem from occurring, they do provide an effective means of identifying and repairing the condition before it affects the continued safe operation of an airplane. Obviously, the procedures are open to continuous improvement. And the proper execution of these procedures must always be emphasized.

The OEMs have determined that all operators would benefit from the survey results. In the near future they will release written Service Communications to emphasize previously published modifications and inspections. They will also highlight preventive maintenance practices, which will ensure the integrity of wiring systems. Design changes are also being considered.

Service Document Review

The second task was to review existing service data, such as service bulletins, all operator telexes, fleet information notices, and other fleet history information related to airplane wiring. The intent of this task was to apply current knowledge of wiring concerns and practices to existing documents and assess the need for additional emphasis on incorporation. Because airplane wiring is not identified as a specific airplane component, wiring problems and their corrective actions are not easily pulled from the databases. Airline maintenance coding did not have a separate code exclusive to wiring. Therefore, a search of applicable databases using key words such as wire, wiring, arcing, sparking, chafing, was used to identify data and documents.

Each Working Group took the lists from the keyword search and reviewed the title and subject of each document for applicability to airplane wiring. Of the thousands of airplane modifications and reports from the field identified by the computer using this search capability, 711 documents were identified as possibly correcting an airplane wiring problem. Because of the historical data available to them, the OEMs were then asked to study each document and its related history. They could then assess whether additional emphasis on fleet incorporation was needed to minimize wiring problems. Some documents were deleted from evaluation because the wiring changes being made were for reasons other than to correct a wiring problem (such as the addition of a new system). Again, the OEM review process was presented to and agreed upon by the ASTF prior to initiation.

Of the 711 documents, the OEMs and ASTF Working Groups agreed that sixty-seven require additional emphasis of some type. Of those sixty-seven, twenty-two have already been or will be upgraded to alert status. Alert is a category that recommends that operators place the highest priority on incorporation. The remaining forty-five documents are undergoing detailed review, prior to assessing the need for, and method of, emphasizing fleet incorporation. This emphasis could come in various forms - an Airworthiness Directive, an Alert Service Bulletin, a new Service Bulletin, re-emphasis of an old Service Bulletin, or other means.

As with the findings from the non-intrusive survey, the OEMs believe that operators will benefit from the results of this service document review. They plan to release written Service Communications detailing the results and recommending that operators reconsider voluntary incorporation of those documents associated with wiring problems.

Finally, for those Service Bulletins that will be upgraded to alert level, the OEMs have agreed to advise and seek comments from the Lead Airlines under ATA Specification 111, Airworthiness Concern Coordination Process. Affected airlines and the FAA will again have the opportunity to provide comments as to whether issuance of regulatory action is appropriate.

Review of Repetitive Airworthiness Directives

The third task parallels an FAA initiative started in 1989. The intent of the FAA initiative was to change from a policy of accepting unending repetitive inspections to ensure continued operational safety, to one where a terminating action is sought to end the repetitive inspections. The reason for this change was to remove the risks associated with human factors that are unacceptable for long-term correction of critical safety problems. The eight ASTF Working Groups were requested to review Airworthiness Directives that incorporated repetitive inspections. They would then determine whether a modification that would terminate the repetitive inspections was available and would provide an effective end to the inspections. This study was not restricted to wiring-related AD's. It included all aircraft systems AD's.

The Working Groups reviewed the AD-driven repetitive inspections currently being tracked at member airlines to identify those related to systems. They found 79 AD's that fit these criteria.

To identify those ADs where terminating action should be mandated, the Working Groups developed a standard process to review, evaluate and make a decision concerning each AD.
Ultimately eight AD's were recommended for mandatory incorporation of a terminating action. Most were related to mechanical flight control and landing gear systems.

Recommendations

The recommendations made by ASTF, and approved by ATSRAC, are contained on pages 9, 13 & 15 of the August 1, 2000, report.

Further Actions

It should be noted that ASTF performed "non-intrusive inspections", meaning that they did not destroy or disassemble any electrical systems during their inspections. ATSRAC realizes that there may be "hidden" problems in electrical systems which would not be detected even by detailed inspections of specific areas. Therefore, ATSRAC has initiated a separate Intrusive Inspection study, directed by Mr. Chris Smith of the FAA, to determine the state of aging electrical systems which are hidden from sight, such as wires inside conduits. The results of this investigation will be presented to ATSRAC at our October meeting.

The Aging Systems Task Force has made a significant contribution to the understanding of aging wiring issues. It should be recognized that all of this work was performed solely on a voluntary basis, without compensation.

Reference:
Pope, Randy. Aging Systems Task Force, Aging Transport Systems, Task 1 and Task 2, Final Report, August 1, 2000. A special report prepared at the request of the Aging Transport Systems Rulemaking Advisory Committee. August 1, 2000