Military aircraft have been taking electronics (or "avionics) into the
air for nearly a century now. But aircraft are a hostile environment, and there
are still unexpected problems. Some of them you just live with. For example,
the U.S. Navy's E-6B electronic warfare aircraft use a lot of old equipment,
largely because the aircraft has been in service since the 1960s. Some of that
stuff wears out real fast, like the ARN-84 navigation system, which has to be
replaced (and repaired) after about 36 flight hours. The navy finally bit the
bullet and got a new, more robust navigation system (the ARN-153) to replace
the older one.
a system designed to be durable, turns out not to be, for unexpected reasons.
The F-18 altimeters were wearing out faster than expected because of
unanticipated vibration. Vibration is a common problem with avionics, and the
altimeters were fitted with a shock-absorbing tray to eliminate the problem
(and save several million dollars in repair and replacement costs each year).
Helicopters have these problems as well. A computer on the MH-60 had a tiny
leak in a seal, that led to the units becoming unreliable after about three
years. Finding and fixing that problem is now saving several hundred thousand
dollars a year.
aircraft are particularly prone to these unanticipated problems. Better
computer modeling, and testing methods in general, have made the problem
manageable. That's important, because avionics have become a larger and larger
component of aircraft cost. Without these improvements in modeling and testing
methods, aircraft would become inoperable. This was often a major risk with
aircraft that were at the bleeding edge of technology. The SR-71 was one
example, as was the Russian MiG-25. The new F-22 and F-35 would not be possible
using the design and quality control methods employed a few decades ago.