Author Topic: Fokker 70 Issues  (Read 9223 times)

EHM-1671 Ben

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Fokker 70 Issues
« on: October 22, 2007, 08:40:58 am »
Hi there guys,

Rico's been having some problems with the Fokker 70 on approach, which I will let him explain the problem further in detail as he will be more accurate than I, but in short the airplane has suddenly nose-dipped down while on finals. Has anyone else experienced this problem? Could anyone shed some light on this?

Thanks!

EHM-1944 Jaap

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Fokker 70 Issues
« Reply #1 on: October 22, 2007, 10:04:15 am »
Strange problem
I made 200+ flights with the F70 (and always with real weather)
and never experienced this problem.

Offline EHM-1695 Hélio

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Fokker 70 Issues
« Reply #2 on: October 22, 2007, 10:05:53 am »
Nose-dipped down? Strange... I thought the problem with F70 was, in fact, too much flare on final!:o

Offline EHM-2097 Andrei

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Fokker 70 Issues
« Reply #3 on: October 22, 2007, 12:12:21 pm »
Never happened to me so I will only shed more darkness on this matter...

I noticed that the flights when Rico had problems were done as ProPilot. I recall there were rumors in the forum about FlightLogger "doing something" to the aircraft, though technically this has no reason to happen. And the respective forum threads remained somehow conclusionless.

I did flights both "normal" and "Propilot" with the F70 and never had such problems (it's still my #1 favorite in the fleet), but I suggest that further posters who would confirm the problem indicate whether it was during Propilot flights.

Cheers
Andrei
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Offline EHM-1703 Philip

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Fokker 70 Issues
« Reply #4 on: October 22, 2007, 04:25:09 pm »
Rico is using FS9 isn't he? I know I tried this aircraft with FSX and it has extensive issues that only the model makers can only correct.
Phil Nutt EHM 1703
 

EHM-0641 Rico

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Fokker 70 Issues
« Reply #5 on: October 22, 2007, 05:33:56 pm »
Hi guys,

EHM v4 F70, on Windows Vista, FS9 with update installed, Duo Core 3.01ghz, 4gb DDR RAM.

The 1st 3 crashed happend at airports where the elevation was between 1200 and 1400ft. As a side note the Decision Height meter on the panel only goes up to 999ft.

The 4th crash happend at EGLL though, where the elevation is 80ft.

Situation:

Inbound to land, approaching respective runway as published on charts, for a ILS approach to land. ActiveSky v6.5 enabled, real weather.

At intercepting LOC, and turning for the glideslope, flaps full, gear down, AP disabled, IFAS of 133 knots, A/c weight less then 44.000 kg.

About 3-4 second after crossing the rwy treshold, the nose of the plane suddenly dips straight down, GPWS goes crazy, and I end up tits up on a stretcher on my way to a hospital if i'm lucky enough to survive :P

...

Driving me crazy, messing up my PP score, EHM is out of UK registred F70's, and it's not the scenery, cuz I made the same flights with other planes and everything went A-okay ...

Sooooooooooooooo.... what's up with this thing??

EHM-2029 Sotiris

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Fokker 70 Issues
« Reply #6 on: October 23, 2007, 04:54:56 pm »
Hi Rico,

first fo all, DH is measured as distance AGL not as absolute altitude. Hence 999ft above the runway is more than adequate as a decision height.

Some points to check:
1 - Lift dumpers: If they're activated earlier they are known to spring open BEFORE landing
2 - Air Brakes: Make sure they're not open

Furthermore, try a slightly higher app speed like 145 or something.

Finally, is it that as you flare you lose too much speed hence the nose down attitude?

One point to try and make sure all is OK is to use your AP all the way to DH and then land to see its behaviour rather than disconnecting as soon as you become established.

EHM-0641 Rico

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Fokker 70 Issues
« Reply #7 on: October 23, 2007, 05:10:05 pm »
Hey Sotiris,

I just tried out what you said, and let the AP land the plane, and the same happened again at LKPR :(

Furthermore, I have 2 screens, one is with cockpit view , the other is with close up spot view, and I can assure you that while armed the liftdumpers do not open before the wheels touch the tarmac, and the airbrake is not open either. Also this test was done with an IFAS of 145 knots as suggested.

Rgds'

btw: I have some problems sending that promised email to you on your staff account, do you have another email addy for me to send it to?

Offline EHM-0654 Murray

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Fokker 70 Issues
« Reply #8 on: October 24, 2007, 10:03:51 am »
Rico, do you own full, paid-for FSUIPC? Turn on control spike damping on the elevators if you do... sounds for all the world like a mad control spike to me, and damping might stop it happening. Only other thing I can think of is install a "proper" flight logger (something like AFS9) and monitor the controls during approach, find out exactly what's going on that way perhaps.
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Offline EHM-2198 Didimo

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Fokker 70 Issues
« Reply #9 on: July 12, 2008, 03:04:59 pm »
Hum, when I posted F70 problems everybody flamed me and I still wear the scars LOL.

Funny thing, my first F70 flight was EHAM to LKPR and like Rico, it crashed on the runway at LKPR.

The "conclusionless" thread was mine. Something very weird on this controversial bird. I can't say WHAT but it was certainly not me. I think it was either the extreme wind shear reported in the same area by other pilots or the PP injecting a random failure (that is what PP documents say it can do).

Anway, I had a few other minor emergencies with this F70 (sorry for the passengers that puked out their meal) but very rarerly. I basically installed the updates from the Fokker Project site to the EHM installation.

I did my whole Class 4 career on the F70 with only one crash on the 1st flight (also my 1st PP flight, sadly my score has been irreparable since then).

As pointed out by others, landing can be slightly tricky. Basically I tamed the thing by using the AP ALT HOLD to do the descent (with max -2500 fp/min), also used the A/T for the speed. On approach and finals I always used around 140 kts.

On landing I never armed the Lift Dampers though they are very useful due to the tendency of this bird to float just above the runway :). The few times I used it was just before touching down. DOn't forget to disable the AP SPEED HOLD after touch down. The "Auto Taxi speed" arming was also very useful.

As for EGGL I don't think it is the scenery. If I remember correctly I did two landings with the F70 (which I took all around Europe) on EGGL, the first with default scenery and the 2nd with payware scenery.

My main issue with the F70 was its highly unusual (never experimented with any other a/c) fuel usage rate. I usually add some 30-40% extra for every flight using the FS estimated fuel usage and believe it or not, I ran out of fuel midway between EHAM and LKPR.

After that on every single F70 flight (many I did) I ignored the FS estimate (which is IMHO almost always sufficient). Instead I went to the EHM flight history and checked all F70 flights made on that same route, the fuel usage was always very high (in comparison with others) so I always took the highest of those and added some 20%. If FS said 600 gals, the actual performance was around 900-1200 gals. With this trick I never ran out of fuel again on this bird.

Other than that I think once you get to know the quirks of the craft you learn how to work around them. If I had the time I would have written a F70 tutorial now that I am virtually "Type Qualified" :)

In spite of these shortcomings (of the Fokker Project I must say, not of EHM) I loved to fly this bird -with some trepidation at times- and remains one of my favourite short haul jets.

 

anything