Twin Otter count?

[kilpicki]

Apparently MAT has 34 DHC-6. Is this more in number than the next largest operator?

[NWONT]

Twin Otter international has about 25 at last count.

[CLguy]

Not sure where you got that number from but MAT does not have that many Twin Otters. Not exactly sure of the total number but less than 20 would be more accurate.

[SheriffPatGarrett]

At their site, they claim to have 24 with two options for the new Viking.
http://www.maldivianairtaxi.com/intrane ... ps-general
What do they mean by "deletion of the beta backup system"? Why would they do that?

[PanEuropean]

At their site, they claim to have 24 with two options for the new Viking.

I think that some of the information published at that web page may be out of date - that page has not been updated for over a year.

What do they mean by "deletion of the beta backup system"? Why would they do that?

It means that there is no beta backup system on the Series 400 aircraft. Annunciation of ground fine range is retained (two blue indicators), but the backup system that intervened by cutting off oil flow to the propeller if the propeller blade angle decreased below +9° without the power lever grips being twisted has been deleted.

Deleting this system simplifies the aircraft.

Michael

[just curious]

And the Groundschool.

[PanEuropean]

And the Groundschool.

No kidding... ...cuts about 45 minutes out of it.

Michael

[W5]

For what it' s worth ( ), the World Airliner Census (published 16-22 Aug this year in Flight International) lists MAT as having 1x -100, 1X -200 and 15x -300, plus 2x-400 on order.

TMA according to that list has 20x -300, plus 2x -400 plus 3 more on order.

[twotter]

Now I'm really confused.. After 25 years, I thought I was just starting to get to know the beta backup system.... And now it's gone.. Damn.. 25 wasted years.. Oh well back to the Beaver.. Again..

[Yankee]

Is a -34 or -27 less likely to have an inflight prop reversal than a -20?

I kinda like the BBS. Makes for a fun takeoff when the microswitch goes t/u.

[PanEuropean]

Is a -34 or -27 less likely to have an inflight prop reversal than a -20?

The design and function of the propeller pitch control system (while in beta mode) on the -20 engine is very different from the design and function of the same system on the -27 or -34 engines. The -27 and -34 engines use the same design. I can't comment on how that affects the probability of having a problem with one design vs. another, however, it is evident from the design change that P&WC thought that the design used on the later evolution engines was a better idea.

Michael

[Lost Lake]

It's been a while but I don't believe the -27 or 34 can go into reverse in flight accidentally

[J31]

Been a long time since my Twin Otter days. I heard that the Beta backup was a product of the -20 PT6 and STOL operations, as a linkage failure could allow the prop to go into reverse in flight at low airspeeds. As noted the later model PT6 design virtually eliminated the possibility of a in flight propeller reversing.

[SheriffPatGarrett]

It did happen at least once...I've seen pictures of the CASA prototype with PT-6.
The wing was bent thirty degrees down but the test pilot managed to land after the
prop went in reverse...I thought it was not possible but it was a long time ago, and CASA now use Garretts...

Couldn't find the picture, but here's a mention of it there(in Spanglish!):
http://www.myetymology.com/encyclopedia ... iocar.html

That same prototype was presented/displayed in the Aeronautical Hall Him Brouget in France,
where it underwent an incident in one of the exhibitions when taking earth, when connecting him the
reverse one of the turboprops before touch-down, reason why it collapsed. In the blow stringers of the wing
were broken both causing a deformation in the same, but the apparatus even rolled until the area of parking
and could be repaired, which gives the idea of the robustness of the airplane

It could not been a Walter as they did not exist then.

[frozen solid]

It says on their web page that MAT are converting all their A/C to WIP floats, because most pilots feel the wips are better in rough water.

I've only flown the twin otter with CAPS. I had always heard the wips were NOT as good at rough water. Obviously I was wrong. I have flown single otters and caravans on wips, and there were some things I liked and some things I did not, but I never felt they were better at rough water than anything else. In fact I felt they were rather lightly built.

I'm curious about it. Are there any twin otter pilots with experience on both who would like to comment?

[PanEuropean]

I believe (but am not totally certain) that the Canadian Aviation Products (CAP) floats are no longer being produced. This is most likely the reason why float operators are switching over to the Wipaire floats. A float is a 'wear part' - they take a certain amount of abuse from bumping up against docks - and therefore they don't last forever. Perhaps close to forever - I've seen some well-maintained, low utilization aircraft in the last year that are fitted with floats that were built in the 1950s - but not forever forever, especially not in a high utilization saltwater environment.

I'm in the Maldives at the moment, I'll take a look in the MAT floatplane pond tomorrow and see what the ratio of CAP to Wipaire floats is. It's not easily possible to get a 100% accurate number, because the entire fleet is never present at the home base at the same time.

I do know that 100% of the TMA fleet is now on Wipaire floats.

I've flown the DHC-6 on both types of float, but I don't have enough experience to be able to comment with any credibility about the handling differences between the two.

Michael

[frozen solid]

That's a sensible sounding reason to want to switch, I suppose. I have heard that the wip equipped twin otters handle more like a conventional floatplane as opposed to the CAP equipped ones, which require the pilot to learn some additional technique. I admire the strength of the CAP float, and also I don't find the handling characteristics to be particularly odious. Perhaps the wip floats are easier to fly on rough water because they give a bit more latitude when it comes to the angle you can touch down at. On first consideration I would have thought the CAP floats were better sea floats due to their deep "V" shape and torpedo-like nose, but perhaps there is something in the way the wiplines handle that makes it easier to plop the plane into the swells. I have some ocean time but not a whole bunch, and none on the DHC6 with wips. I did like the wips on the single otter, but I did find that for beaching they were very thinly constructed and were easy to damage. You could flare the thing onto the water like a taildragger, though, and the wips would let you get away with it, whereas if you try that in a twin with CAPs, they will bite you.

I find this an interesting topic, especially since I don't have very much experience with ocean swells. Fortunately, every time I've had to go to the ocean, I've been able to find a good place to hide behind to avoid the swells

[Mad Flying Ace]

Last I heard, Borek owns the CAP 12000 STC, and thus builds and maintains them.

So - they are still available.

regards

MFA

[FriendlyBear]

Yes, that is correct... Borek ownes the CAP 12000 STC they are maintained and built in YYC. I remember Steve Penikett telling us that they now owned the rights to CAPS...
I also remember TMA not being able to get access to the CAPS floats from Borek so that is why they went with the Wipeline floats initially.
The Bear
Post Edit: I just spoke to an old friend who still flies down in the Maldives and he told me that Borek still owns the CAP 12000 STC.

[CLguy]

Frozen Solid, you heard correct regarding the Wips vs Caps on the Twin Otter.

[PanEuropean]

Last I heard, Borek owns the CAP 12000 STC, and thus builds and maintains them. So - they are still available.

Although I believe that you are correct when you state that KBA owns the STC for these floats, that alone does not mean that they are commercially available. It is very common in our industry for STC owners to not make STCs that they own available outside of their own organization. This can be due to many reasons - possibly the STC owner has no interest in commercially marketing the STC (for example, they want to 'stick to the knitting' and run their flight operations, and not become a manufacturer, with all the headaches and support obligations that involves), possibly they want to keep the STC for in-house use only because it is easier to fulfill continuing airworthiness requirements that way, possibly the STC holder does not want to shoulder the burden of liability that would come with others using the STC, etc. It might also be that it does not make economic sense for the STC holder to market the STC... in the case of Twin Otter floats, it is possible that because of the volume of sales involved, it would be difficult to manufacture CAP floats (on a custom, small volume level) at a price that could compete with Wipaire floats (a high-volume product). It's also possible that a company could have bought a STC simply because holding the STC makes it easier for them to service and support their own aircraft that are equipped with that specific STC.

So, the fact that a STC exists and that the STC owner is in business does not, a priori, mean that the STC is available to the public. I'm not saying this with any specific reference to KBA and their CAP float STC, the concept applies worldwide to all STCs.

Michael

PS: I went over to the MAT dock yesterday and did not see any aircraft with CAP floats parked there. That doesn't mean there are none - because it is rare for the whole fleet to be back at the dock at the same time - but, of the 9 aircraft that were docked, all 9 were on Wipaire floats.

[Rowdy]

This may have not come to fruition.. but I do remember reading that PK had done some licencing with KBA to produce the CAP 12000s.

Did this fall by the wayside?

[Maldivesbound]

Hello, I am off to the Maldives soon and I wanted to ask if the TMA and MAT fleets are all on Wips, or if there are some birds still on CAPS? What are the current fleet counts??
Thanks again!
Maledivesbound