Aviation Week & Space Technology - 3 November 2014

The team had fi ve core members. They did not work full-time

on NFF, but met weekly to address NFF problems. Other ex-

perts were also tapped. “You have to have a structured ap-

proach,” Saltigerald insists.

Arinc 672 gave NFF staf a common language and a com-

mon matrix to help locate root causes. Common language is

essential because solving many NFFs involves at least three

parties: an airline, airframe OEM and component OEM.

A structured approach and core team institutionalize NFF

experience. “You need to build a knowledge base and good

documentation because you don’t want one employee to take

all the NFF knowledge when he leaves,” Saltigerald says.

Data on removals is essential. He says it should contain as

many relevant parameters and cover as long a history as pos-

sible, back to birth if feasible. Airlines usually have the most

important data, but component OEMs do not always get this

data to help design out NFFs in the future. Contract language

or mutual interest should ensure necessary data are shared.

Air Wisconsin was especially concerned with rogue units.

“Rogue units can ruin an inventory,” Saltigerald says. “Good

parts chase rogues and mean time between unscheduled re-

movals [MTBUR] suf ers.”

NFFs and rogues can occur in any avionics area. “Anything

with buttons you touch and moving parts can be in the top

10,” Saltigerald notes. “But sometimes it’s computer chips

and PC boards that you are not even touching. Each NFF

situation is dif erent and dynamic.”

Saltigerald has high hopes for the future. He says good work

is being done on electrical wiring interconnection systems

(EWIS) to fi nd factors that contribute to NFFs and hidden-

failure modes. He hopes RFID tagging will alleviate some prob-

lems by recording part and serial numbers, how long a part has

been on an aircraft and possibly past fi ndings by mechanics.

Other technology also looks promising. Better data analyt-

ics, fault isolation, troubleshooting and predictive maintenance

MRO Edition

MRO24 AVIATION WEEK & SPACE TECHNOLOGY MRO EDITION NOVEMBER 3/10, 2014 AviationWeek.com/mro

AVIONICS

A

irframe OEMs have the power—and incentive—to play a

major role in resolving NFFs. Airbus’s NFF policy for A320s,

A330s and A340s seeks to ensure that when avionics com-

ponents show an error, all applicable maintenance actions and

memory reading are done to identify the root cause of a fault

message and avoid unnecessary removals. Thus, if a removed

component is shipped to its supplier with all required supporting

data and tests NFF, test costs will not be charged to the airline.

The decision on whether to remove a part is made by the

airline. When a component is turned in, its OEM or the OEM’s

authorized repair station contacts the airline to learn the reasons

for removal and obtain historical data. Airbus may get involved to

ensure all causes are documented, resolve interface issues and

maintain its NFF policy.

Responsibilities are very specifi c. Airlines must supply data

including the initiating pilot, maintenance or post-fl ight reports,

results of built-in test equipment (BITE) tests, troubleshooting

data or return-to-service tests and historical data on all its NFFs.

Airlines must also follow Airbus’s fl ight crew operating manual,

operation engineering bulletins and maintenance recommenda-

tions. They should keep maintenance records by component se-

rial number. If the same component is NFF three times in a short

period—typically 12 months—the airline should send it to the

OEM for in-depth investigation. Rogue units can also be spotted

with historical records.

Airbus’s avionics OEMs must keep historical data by se-

rial number of all components repaired in their shops. Data

must include warranty history, total repair history, reasons for

removal, tests, NFFs, modifi cations and all work performed.

The OEM should also do the in-depth investigation of high-

frequency NFFs.

This policy applies to avionics electronic and electric equip-

ment, but not to proximity switches, pressure transducers, circuit

breakers and hydraulic, mechanical and engine parts.

The Airbus policy at least reduces airline NFF costs. Over

time, it should also reduce NFFs, yield better understanding of

centralized systems on the aircraft and greater understanding

of NFFs by both airlines and suppliers and improve the trouble-

shooting manual. c

AIRBUS SEEKS

AIRLINE-OEM

COLLABORATION

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