JB wrote:
> They've been orphans in QF operations for a very long time. Whilst I'm sure
> there is a cost, I doubt that it's enough to really be a problem. There is
> already plenty of expertise in place with regard to maintenance of these
> engines.
I suspect it depends on exactly how the deal is structured. Are they going PFI,
is it going to be fully RAAF, some hybrid? On the orphan issue, does Qantas
want to get rid of them because they're too small, because they _are_ orphans
and not cost-effective, or some other reason? The other issue might be how
widely available parts will be for the JT9 for 20 years or so; after all, the
last new JT9D was produced in 1990. The JT9D seems likely to disappear from
service long before the other engines.
> There are no pilot training/currency issues. If that's all the RAAF have,
> then they won't have a currency or training problem. In practice, I operate
> all three types of engine, and there aren't any practical issues, other than
> remembering (or not) a few different limits. Procedurally more or less
> identical.
Good to know. What's the thrust on the JT9s, compared to the other engines?
Payload capability operating from Learmonth and Tindal is likely to be a factor.
Guy
matt weber wrote:
> On Mon, 30 Jun 2003 22:19:42 GMT, Guy Alcala
> <g_alcala@no-spam> wrote:
>
> >JB wrote:
> >
> >> They've been orphans in QF operations for a very long time. Whilst I'm sure
> >> there is a cost, I doubt that it's enough to really be a problem. There is
> >> already plenty of expertise in place with regard to maintenance of these
> >> engines.
> >
> >I suspect it depends on exactly how the deal is structured. Are they going PFI,
> >is it going to be fully RAAF, some hybrid? On the orphan issue, does Qantas
> >want to get rid of them because they're too small, because they _are_ orphans
> >and not cost-effective, or some other reason? The other issue might be how
> >widely available parts will be for the JT9 for 20 years or so; after all, the
> >last new JT9D was produced in 1990. The JT9D seems likely to disappear from
> >service long before the other engines.
> >
> >> There are no pilot training/currency issues. If that's all the RAAF have,
> >> then they won't have a currency or training problem. In practice, I operate
> >> all three types of engine, and there aren't any practical issues, other than
> >> remembering (or not) a few different limits. Procedurally more or less
> >> identical.
> >
> >Good to know. What's the thrust on the JT9s, compared to the other engines?
> >Payload capability operating from Learmonth and Tindal is likely to be a factor.
> >
> >Guy
> JT9D's covered a wide range, but I believe the 767-200's have 7R's,
> which in this application are 50,000 pounds thrust each. Runway
> requirement/lift capability is rarely much of an issue with the -200.
It appears that the Qantas 767-200ERs probably have a MTOW of 350,000 lb., judging by
a Boeing 767-200/200ER runway length takeoff chart* which shows a/c with the
JT9D-7R4D/7R4E or CF6-80A/A2 engines for that weight, and I agree that at that MTOW
takeoff distances should rarely be a problem, even in hot conditions.
*Found on the web some time back.
> You can get several variants of the CF6-80 for the 767-200ER, as well
> as PW4000's. For thrust pick a number from 50,000 to about 57,000
> pounds.
Takeoff Runway length Charts for 200ERs with MTOWs of 380,000 (CF6-80C2-B2 or PW
4052) and 387,000 lb. (CF6-80C2-B4 or PW4056) on hot days (ISA +17C) show that runway
length is definitely becoming a factor. So, if they stick with lower gross weight
200ERs, no problem, but if they want to maximise payload and fuel offload in hot/high
conditions, the lower gross weight JT9D-powered a/c aren't going to cut it. While
the JT9D 767s shouldn't be anywhere near as limited in TOW as the USAF KC-135Es were
when based in the Gulf (or the really pitiful KC-135As), that still could be a
significant operational limitation. It will be interesting to see what the RAAF
decides to do (or rather, what the Government's willing to pay for), given that used
767 airframes seem to be relatively cheap and available these days. Guess it depends
what the market for freighter conversions is as well.
Guy
JB wrote:
> > It appears that the Qantas 767-200ERs probably have a MTOW of 350,000 lb.,
> judging by
> > a Boeing 767-200/200ER runway length takeoff chart* which shows a/c with
> the
> > JT9D-7R4D/7R4E or CF6-80A/A2 engines for that weight, and I agree that at
> that MTOW
> > takeoff distances should rarely be a problem, even in hot conditions.
>
> Their max t/o weight at the moment is 146,000 kgs. It used to be 155,000,
> but was reduced when no longer needed for long haul ops. Registration fees
> are based on this weight, so their is no point having more than you need.
Thanks for the info. Even 155,000 kgs does seem rather lacking, although they
might be able to boost that during any freighter conversion.
> > Takeoff Runway length Charts for 200ERs with MTOWs of 380,000 (CF6-80C2-B2
> or PW
> > 4052) and 387,000 lb. (CF6-80C2-B4 or PW4056) on hot days (ISA +17C) show
> that runway
> > length is definitely becoming a factor. So, if they stick with lower
> gross weight
> > 200ERs, no problem, but if they want to maximise payload and fuel offload
> in hot/high
> > conditions, the lower gross weight JT9D-powered a/c aren't going to cut
> it. While
> > the JT9D 767s shouldn't be anywhere near as limited in TOW as the USAF
> KC-135Es were
> > when based in the Gulf (or the really pitiful KC-135As), that still could
> be a
> > significant operational limitation. It will be interesting to see what
> the RAAF
> > decides to do (or rather, what the Government's willing to pay for), given
> that used
> > 767 airframes seem to be relatively cheap and available these days. Guess
> it depends
> > what the market for freighter conversions is as well.
>
> It all rather depends what you want to do with them. If you are buying
> tankers, then with max fuel loads you will end up with t/o weights around
> the 150 tonne mark. No performance problem at all. I you want to carry 30
> tonnes of freight, and play tankers simultaneously, then you're looking at
> the wrong aircraft. You will need something substantially bigger, and more
> expensive.
They certainly should have more ability to act as deployment tankers (also
carrying freight/personnel) than anything based on a 707, so the higher gross
weights may well matter. Depends how often you think you'll need to operate out
of area, and how much tanking help (from allies) you can expect for the transit.
> As for 767s lying around the countryside...be interesting to see what
> condition most of them are in. Remember, you can't look at 300s, as they'll
> drag the refuelling boom on the ground when they lift off.
Has that actually been established, or is it more a question of 'yeah, you could
do it, but it will screw the takeoff and landing distances because you can't
rotate as much?' I wonder if the A330 has the same problem (a bigger
tanker/transport than the 767, but maybe too big/heavy for many of the bases the
RAAF might want to work from, in addition to the other issues).
Guy