Aviation Maintenance Magazine

Avionics Maintenance Heats Up

22 Dec 2011

By Charlotte Adams

The temperature’s rising in airline avionics shops. The weak economy is pushing carriers to cut repair and maintenance costs but spurring original equipment manufacturers (OEMs) to maximize returns in the aftermarket. These tensions have created a more adversarial relationship whose latest symptom is the struggle over data access.

“We have seen a fall in customer support, which may be driven by the fact that some OEMs and airlines are competing against each other for the same MRO dollars,” observes Ebb Segars, general manager-component maintenance operations with Delta TechOps.

While engine and airframe issues grab headlines, avionics maintenance is no backwater. Although old analog systems were highly complex, the flood of digital electronics is more challenging. System-level, functional integration is proceeding apace, accompanied at the other end of the spectrum by exponential increases in device densities. These trends, combined with data access issues, continue to test airline shops and their third-party partners.

Inflight entertainment (IFE) has driven much avionics growth, but many other components are also “wired,” to use ARINC’s basic definition of avionics. Avionics, for example, now includes lowly faucets, lavatories and flashlights. A Boeing rep at ARINC’s Avionics Maintenance Conference (AMC) joked that air sickness bags have not been wired “yet.” Even simple windshield wipers can be a puzzle because of a hybrid integrated circuit in the board, says Marijan Jozic, ARINC’s AMC vice chairman. AMC is the primary forum for the resolving airline avionics issues with suppliers and airframers.

Jozic says that avionics sometimes gets a bad image because it’s so complex and opaque to non-experts. People aren’t that upset if you ground an aircraft for a week because there’s a crack in the fuselage, he says. But “if you ground an aircraft because of a missing signal in one of the sensors, everybody’s upset—you can’t see the damage.”

“Sometimes you have to spend hours and hours troubleshooting,” Jozic says. “Then you find a pin in a connector that is pushed back and making no contact.” The fix takes about half an hour, but everybody is upset again because it’s just that simple. “It is amazing that a big 747-400 stays on the ground for a day for just one stupid pin.”

Avionics-related “aircraft on the ground” (AOG) incidents happen, agrees Jens Latendorf, Lufthansa Technik (LHT) production engineer, component maintenance, and AMC representative. But negative consequences like long-downtimes can be minimized by spare parts and availability planning, plus appropriate logistics, he says.

LHT is also concerned about the trend to “dedicated” chips, which involves more difficult repair processes and raises obsolescence risks. A quality failure at this level, moreover, could have an outsized impact because of limited supplies.

Delta TechOps “monitors on-wing reliability very closely—down to the individual serialized component,” Segars says. “We have data systems that alert us when something needs extra scrutiny during the repair visit.” Segars says that “the majority of removals are still due to hardware faults.” The environment a component operates in has a big impact on overall system reliability, he adds. LHT, however, finds that newer aircraft can raise more issues with software than hardware.

Connectors and associated wiring, including support hardware, continue to be a focus and problem area, says John Laughter, Delta Air Lines senior vice president, maintenance operations. “Many new configurations greatly improve these areas of impact.” But the increasing regulations of SFAR 88—the special federal aviation regulation on fuel tank system fault-tolerance evaluation requirements—and electrical wiring interconnect system (EWIS) “require more program investments in training and manpower to maintain electrical/avionic systems, including LRU [line-replaceable unit] head units, compliantly,” Laughter says.

But it is tricky to generalize. Delta Air Lines has not seen an overall increase in the operational impact of individual avionics-related AOG events in the past four and a half years, Laughter says. Just the opposite. The impact of avionics-related AOG events has decreased by 24 percent during that period. “Events appear to be occurring more often but with less individual impact,” he says.

Issue Du Jour—Data Access

The next big battle will be over IP [intellectual property],” Jozic predicts. “At AMC there were a lot of questions from airlines who are asking for data and not getting it.” Data access is a potentially serious issue, but nobody’s audited it yet, Jozic says. “Nobody’s exercised the issue.”

At the heart of many AMC discussions was the OEM’s component maintenance manual (CMM). Airlines that purchase supplier-furnished equipment (SFE) are supposed to receive Level 3 CMMs—with information all the way down to board repairs. But carriers are not always getting this. Although airlines don’t always know this, the airframer’s product support assurance agreement entitles them to receive Level 3 CMMs, test equipment specs and diagrams, and access to procurable piece parts, says Mitch Klink, ARINC’s AMC chairman.

Some B787 CMMs, for example, are being written at Level 1—for box-level, go/no-go test. While this may be a timing issue, with warranties in effect, it is still a sore point. Nor are the airlines always getting complete documentation for OEM repairs.

New avionics units sometimes come with “tiny CMMs,” and CMMs for older avionics components are sometimes being thinned down from Level 3 to Level 2 by the removal of repair procedures in the latest revisions, Jozic says. (Level 2 involves replacing circuit cards instead of repairing them.) Or the CMM simply states: If the LRU is out of limits, send it to OEM for repair, he says.

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