Features

May 2009 Issue

Unapproved Parts

Deciding to skimp on new turbocharger wastegate controller oil lines is not a good choice.

Keeping an older, or "aging," aircraft airworthy is a balancing act of sorts. On one hand, itís nice to simply replace rather than repair parts and components when they go bad. On the other had, and since some parts and components are increasingly rare, the cost of changing them out can be stratospheric. The balancing comesóat least for meófrom deciding what to replace and what to repair. If I replaced every part or component presenting an issue, instead of repairing it, Iíd have no money left over to use for other parts and components. Or to fly the darn thing in the first place. Itís no huge secret that many parts installed on older aircraft are generic automobile components from the era in which they were first designed. Items such as window cranks, ashtrays and the like certainly qualify, but so do many electrical components like relays and even generators. Parts like light bulbs and cabin speakers frequently can (and perhaps should) be replaced with a modern equivalent. Discussing modern lubricants is an entirely different subject, as is the "owner-produced" part. Meanwhile, operators of older aircraft often will find themselves needing, say, a new generator only to discover it is no longer available from traditional sources. Scrounging then becomes the order of the day, perhaps for a rebuilt example. Eventually, the scrounger will discover the generator was first used on, for example, a Ď46 Buick and some guy in Arkansas has a warehouse full of them heíd be happy to sell. The only problem is they donít have the right part number or are missing a special diode. The situation then becomes one of convincing the FAA-certificated technician doing the work to sign off on the obviously identical-but-unapproved part.

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