"Harry Andreas" wrote in message
...
In article , "Diamond Jim"
wrote:

"Harry Andreas" wrote in message
...
In article .com, "~^
beancounter ~^" wrote:

in going through some old navy paperwork i came across this..
"the f14 requires 50 to 60 maint hrs every hour it flies, while the
super hornet needs 10 to 15 maint hrs for each flight hour...

if true, thats a hell of a difference...

Those are more or less the numbers that I've heard.
BTW, the maint hrs/flt hr is still going down.
It's lower on the E/F than the C/D (so I've heard).

--
Harry Andreas
Engineering raconteur

Having had the additional duties several times as Asst. MaintO and MaintO
in
a squadron, (for earlier generations of aircraft) and spending a number
of
years in DOD (mostly DARPA), I can tell you that those figures are pretty
solid. The more modern an aircraft is, the more it is "plug and play" to
borrow a computer term.the aircraft is. Just about everything is a SECREP
(secondary repairable). Organizational Maintenance will unplug and swap
boxes, board, modules etc. on the aircraft, replace with new/repaired
items,
test and if passed "up the system". If it fails then another is plugged
in
its place. Heck even bad wires are replaced as part of a harness
assembly.

The SECREP then goes to Intermediate or Depot Maintenance for repair, and
after repair it goes back into the supply system. About the only, "old
time
maintenance" that takes place on an aircraft anymore is cleaning,
polishing,
fueling, ordnance, maybe a little adjustment on the gun or hard points
etc.
and occasionally some body work/repair, just about everything else is
swapped. This swapping out means that an aircraft can be turned around
quickly, and doesn't have to wait until the specified hours of
maintenance
have been performed. In other words it could actually be back in the air
as
hours of maintenance are still being performed.

When the hours are figured (maintenance hour per hour of flight, mean
time
between failure) or whatever the "bean-counters" want to know, it
usually
included all the maintenance hours throughout the system organizational,
intermediate, or depot. (New manufactured items are not included in these
calculations but may be in other service wide figures. As everything is
in
the computers, these figures can be easily recovered for an individual
part,
aircraft, squadron, wing, ship, fleet, service, manufacturer, year, month
day, hour, what ever keeps people happy, and employed.)

And as with all figures, people can manipulate them to show just about
anything they want to show in any light. In fact many build a career on
doing just that.

Jim,
as I think I've mentioned, I've spent a lot of my career working on
various
radar designs, starting with the pre-production APG-65 in the pre-prod
F/A-18A's.
The engineering community has spent a huge amount of time and money
to make these airborne electronics low maintenance and highly reliable.
In terms of reliability, current circuit card designs have reliability
lifetimes in excess of the rated airframe life. Some stuff you might never
have to take out of the aircraft.
That adds a new dimension to maintenance, because if it works out as
planned, it's no longer practical to have an "I" shop aboard ship or
land base. "O" level pulls the box and in some cases the card from the
box. It's cheaper and faster to send a broken card back to depot
and replace it from stores. And with the complexity of some of the cards,
they
might not be repairable in the field anyway. Think of a .020 diameter
(0.5mm)
solder joint buried under a part with 400 others...
This doesn't cover all electronic parts, of course, but certainly a lot.
At least of the ones I've been associated with lately.
Most everything than can be put on removeable cards, is, and that helps
maintenance turnaround time as you have noted.
Mean time between critical failure is way up and mean time to repair is
way
down.

cheers

--
Harry Andreas
Engineering raconteur

I certainly didn't mean to give the impression that the lower maintenance
hours was due only to "pull and swap" maintenance. The improvement in
design, materials, etc. has increased reliability immensely, especially in
the electronics field. I also agree that the Intermediate Maintenance
workload has been reduced in many ways. Not only is it cheaper and quicker
in many cases to draw a spare from the supply system and send the defective
one back to depot maintenance for repair, it is also economical in many
cases to toss the defective one into the recycle bin to be sold as scrap.

Now if someone could just figure out how to do the same with hydraulics.