Shelf Life: What Does it Mean?

By H. Dean Chamberlain
Reprinted with permission from FAA Aviation News

A lesson about shelf life - or how I learned to buy two new turn coordinators. As a relatively new aircraft owner, I have learned many expensive lessons. Most of those lessons were discussed in my previous hopefully humorous attempts at explaining the joys of being a new owner of an old aircraft. I would like to add a postscript to my last article on the subject.

The week before Thanksgiving, I had the 'pleasure' of buying a second new turn coordinator (TC) from Mid-Continent Instruments in Wichita Kansas. The first unit was dead on installation (DOI), which should not be confused with dead on arrival or DOA. As I explained in my other articles on the upgrading of my old Piper Tripacer, the project took much longer, years longer, then expected. The project included the replacement of all of the flight, navigation, and engine instrumentation.

Buying a new instrument is not the same as having a new instrument. When I ordered all of the new instruments from various suppliers, the last thing I thought about was the term 'shelf life.' However, shelf life can be critical when working with aircraft. Basically, shelf life is how long an item can be shelved or stored while remaining usable. In the case of my DOI TC, I dutifully boxed it up a few weeks ago and sent it back to the factory after having exchanged emails with a company representative. When I never received any word about the TC, I called the company and talked with a customer service representative. A day later, I was contacted with the post mortem report. The TC was dead. The apparent cause was the expiration of its shelf life. According to the woman who called me, the bushings had died and some other items were not working.

Although never used, the unit failed to operate on its first flight. The woman I spoke with said it had been manufactured years earlier and was out of warranty. The unit had 'died' in its shipping box.

She offered to repair the unit with the exception of correcting a small, visual defect, for about $190. The blemish would cost more she said. The repaired unit would come with a 90-day warranty. In discussing my options with her, I chose to buy a new unit for almost $500. The reason I chose to buy another new unit was its one-year warranty. If this unit failed, I wanted some recourse.

When I purchased my TC and all of the other items, I really didn't think about warranties and limited shelf life. But then, I didn't think my upgrade project would stretch out over three and a half years. So, when I was buying items for the aircraft, I had no idea that all of the warranties would expire before the items were installed.

The result, in the case of my DOI TC, was the cost of buying another new unit. It was an expensive lesson. Now, I pay attention to manufacturing, shelf life, and warranty dates.

A lesson I have learned. Three days before I bought my second new TC, I bought new tires for my sport utility vehicle. Having remembered a recent network news story about recommended tire life dates, one of the first questions I asked the dealer installing the tires was when were the tires manufactured. I wanted 'new' tires, not unused tires made several years ago.

The folks at Mid-Continent were pleasant and very helpful to work with. It was not the company's fault my first TC was not installed upon receipt. It was my fault for not thinking about why some items come with a shelf-life date. The date is there for a reason. Just like bread has a sell by date to ensure its freshness, so do some aircraft products. My problem was the uncertainty and delay that comes with a part-time major upgrade project.

If your aircraft goes into the shop for work, warranty dates should be no problem. But if your aircraft is a 'basket case' or is a kit project or undergoing a major upgrade, then your completion date may be unknown.

In such a case, my recommendation is to avoid buying date limited items until the absolute last minute. In my case, I would not have bought my limited warranty instruments that were out of warranty before installation or my now two-generation old IFR GPS until the day before the plane was ready to fly. If I had waited until last June when the aircraft finally flew, my instruments would still be in warranty, and I would have a different GPS in the aircraft.

All of my efforts to save on buying my instruments and GPS when I had the money and for what I thought were good sale prices turned out to be very costly mistakes. In hindsight, it would have been cheaper to have saved the money and bought the instruments just before needed for installation.

As I have written before, please learn from my mistakes and save yourself some money. So read and understand all warranties before you buy and buy just before flight. The time, money, and warranties you save will add to your project's enjoyment.