Heres the question.


On the older 100 series AC ( very low VIN #'s) running dash 20's. How does one up gross this AC? Does a guy have to bolt 300 series wings (new spar etc..) to mount the 27's? Can you mount the 27's on the 100 wing? If so does the frame allow you to carry more weight ie. 12500?

My apologies to the DHC6 gurus out there for the possible stupidity of the questions but these questions were asked to me and I had no idea.

Thanks for any help

We have -27's on all our 100 series.

I've yet to hear of any operator that was able to get a weight increase on 100 series Otters.

How many 100 series do we have left? Not many I'd imagine.

What about for the 200's?

If I remember correctly, and it has been a few years, the wings on the 100 series are life limited. The ones I flew had 200 series wings on them Not sure about the the spar stuff. There are some real TO expert AMOs out there. Give them a call.

As to the 27s..what JC said. One of ours was converted from the -20s and I dont recall it being a big deal...the conversion...the money...not so much...the nicer to operate engines...yes.

You might also want to post this on the maintenance forum..Probably more knowleable types there

What about the -34 conversion?

I heard that the starter won't come off without dropping the engine.

Is this true?

Nah! The maintainers came and rescued me at Sheep Creek, and took 30 minutes to change it. They're great engineers, but 30 minutes for 2 guys to change an engine would be pushing it.

The company I contract for used to have a 100 series Twin otter serial #29 with -34's. They still have Twin otter serial #27 with -34's

Is this common or a rarity to have 100's with -34's ?

MAF Australia has an STC to put -34s on a 200 and up the gross to 12500. As far as I know the upgross on the 200 is not available anywhere else

As far as I know, it is such a paperwork nightmare as to not be worth it at all to re-certify a 100 or 200 series Twin to 300 series limitations under CDN reg.. There are a fair amount of 1 and 200 series twins operating for Air taxi in the Maldives, all of which have -27s, none of which have a 12500 gross weight. With 300 wings, the only other true limiting factor, from what I was told, is the tail: it lacks control authority to be able to handle 300 series min control specs at 50 lbs torque (max t/o power for 300s). If you look, 300s have more vortex gens on the vert tail, 100-200s have less (none?? can't remember ). Also, though it isn't legally allowed, if there are 300 wings on, you can certainly use 50 lbs to break water, then power back to 42.5, as briefed of course .

D-Iced wrote: Also, though it isn't legally allowed, if there are 300 wings on, you can certainly use 50 lbs to break water, then power back to 42.5, as briefed of course .

Why would you do something that's not legally allowed?

It is not possible to increase the MTOW of a Series 100 DHC-6 (which is 11,569 pounds) to the same MTOW as the Series 300 aircraft (which is 12,500 lbs). I believe that this is due to structural differences in the fuselage of the Series 100 when compared to the Series 200 and 300 aircraft.

It is possible to fit -27 or -34 engines to a Series 100, but the torque limitation of 42.5 PSI (equal to 550 SHP) remains in place. Similarly, when a -34 engine is fitted to a Series 300 aircraft, the torque limitation of 50 PSI (equal to 620 HP) also remains in place.

As Noront posted, MAF in Australia has a STC to increase the MTOW of the Series 200 aircraft to 12,500 pounds and to fit -34 engines.

Several STCs are available to fit -34 engines to the Series 300 aircraft. There is some benefit to doing this for 'hot and high' operations, and it may make economic sense if a Series 300 has two really run-out -27s on it and the overhaul of those is going to cost big bucks. However, for operations in Canadian environmental conditions, it might be tough to justify the expenditure to upgrade to -34s. Basically, all you get is more temperature margin and a slight increase in TBO.

I have another one for you Otter Guru's out there...

This time, I was wondering why some Twin Otter's (series 100's/200's I've seen) do NOT have the wing fences on top....

Any idea's

I don't believe that the wing fences were part of the type design for the Series 100 and 200 aircraft - I think that they were introduced at the beginning of Series 300 production, with effect from SN 231.

Below is a picture of SN 009, which was taken in the early part of 1966 (note the partially completed Toronto-Dominion Bank tower in the background) - it is not fitted with wing fences.

Michael

How come EVERY 100 and 200 I've flown has had them?
QOQ, LXP, GQE, JAW, GQH, MHR, QKN, WTE
Could it have been the floats attached to the bottom?

Edited for photo size

seniorpumpkin wrote:How come EVERY 100 and 200 I've flown has had them?

Could be due to a variety of reasons.

It's possible that the wing fences are part of the equipment package required for floats (either Canadian Aircraft Products, or Wipaire). It's also possible that the wings on these aircraft are not the original wings (due to the originals having become time-expired), and the new wings that were fitted were equipped with the fences, and there is no restriction that states that the early series of aircraft may 'not' have wing fences fitted.

It's also possible that the wing fences were retroactively introduced to the Series 1, 100 and 200 aircraft by way of a Modification.

It's the weekend, and I'm not going to go into the office just to look up the reason why...

Michael

FYI.

RW Martin currently has the increase gross weight STC for the 200 series twin Otter (200HG). They do structural modifications to the fuselage and add the -27 or -34 engines. This modification is anywhere from 350k - 800k depending on the modifications the exisiting aircraft has.

They also have a STC to convert a 100 series to a 200 series would would then be elegable for the 200HG package.

The 200HG operates to the same limitations of the 300 (Max torque, Takeoff weight, etc).

Polarpilot wrote:FYI.

RW Martin currently has the increase gross weight STC for the 200 series twin Otter (200HG). They do structural modifications to the fuselage and add the -27 or -34 engines. This modification is anywhere from 350k - 800k depending on the modifications the exisiting aircraft has.

They also have a STC to convert a 100 series to a 200 series would would then be elegable for the 200HG package.

The 200HG operates to the same limitations of the 300 (Max torque, Takeoff weight, etc).

That sounds like quite the upgrade ! I'm surprised that more operators of the old ones don't take advantage of this. Perhaps they've kept it off the shelf ??

Ikhana Twin Otters Live Longer

Ikhana Aircraft Services, a specialist in extending the life of the popular DHC-6 Twin Otter based at French Valley Airport in Murietta, Calif., has been remanufacturing aircraft long before the term became popular in aviation circles. Ikhana–the name stems from the Choctaw word for knowledge and intelligence–was created from the merger of engine specialist Total Aircraft Services and R.W. Martin, the originator of the Twin Otter VistaLiner conversion that opened up spectacular aerial tour opportunities by upgrading fuselages with huge passenger viewing windows. R.W. Martin converted 45 Twin Otters to the 19-passenger VistaLiner configuration, and many are still flying; some are now returning to Ikhana for maintenance and re-lifing.

The re-lifing of the DHC-6 Twin Otter is Ikhana’s bread-and-butter. In 1996, R.W. Martin’s highly trained sheetmetal technicians started disassembling and rebuilding Twin Otter wing boxes; then, in 2007, Ikhana’s workforce took over and, now, between the two companies, more than 115 sets have been rebuilt. The wing box is the major wing structure between the front and rear spars and it has a life limit of 25,000 to 33,000 hours or 50,000 to 66,000 cycles, depending on the model.

When a set of wings arrives or is removed at Ikhana’s facility, the technicians first un-rivet the lower wing skin then pressure wash and degrease the structure and remove all fatigue-critical components. Each wing box goes back together with new stronger stringers, larger doublers and thicker skins, all coated with epoxy primer to prevent corrosion.

The Ikhana DHC-6 Re-Life Wing Box STC extends the life limits to 45,000 hours or 90,000 cycles for the -300 series and 49,000 hours and 98,000 cycles for the -100 and -200 Twin Otters. Ikhana also offers an STC to extend the life of earlier design wing boxes, adding structure to increase the fatigue life to 35,000 hours and 50,000 cycles (up by 10,000 hours/20,000 cycles).

Fuselage Re-Lifes

Now Ikhana (Booth 3424) is starting to see Twin Otters with fuselages that are bumping up against their 66,000-hour, 132,000-cycle life limit and therefore in need of re-lifing. Flight controls share the same life limit as the fuselage, and Ikhana can re-life those as well. Nacelles are brought to life limits of 45,000 hours and 90,000 cycles. All re-lifed components receive new data plates, part numbers and serial numbers so they are “zero time” once installed, according to Ikhana. Once re-lifed, these components are interchangeable with the original components.

Roughly 500 Twin Otters were built before de Havilland shut down the production line, and now Vancouver-based Viking Air has resurrected the line with the new Twin Otter Series 400, of which more than 60 have already been delivered.

While heavy-duty work on Twin Otter airframes is much of what Ikhana does, the company also offers a host of Twin Otter services, including avionics, electrical, interiors, engine upgrades, paint, engineering, component manufacturing, certification and maintenance.

Ikhana Aircraft is also a Viking Air factory-endorsed service center for the Twin Otter and DHC-7, and the company buys more parts from Viking than any other customer. Ikhana has also done modifications and supported engineering work on the Gulfstream GII/GIII, Bombardier Challenger series, Boeings from the 727 through 787 and DC-10, Lockheed C-130, Hawker jets and Beechcraft King Airs.

The company can deliver an entirely remanufactured Twin Otter for about $5 million, significantly less than the cost of a new one. Another benefit of choosing an Ikhana reman is that buyers have a choice of avionics, where the new Viking Series 400 comes standard with a single offering: Honeywell’s Primus Apex flight deck.



X2 Models Available

A Twin Otter X2 was undergoing a complete re-lifing at French Valley during AIN’s visit, and this airplane is available for about $4.8 to $5.2 million, depending on the final avionics and options selections. The X2 includes new Pratt & Whitney Canada PT6A-27 engines, all-new wiring, all of the Ikhana airframe Re-Life packages (fuselage, wing box, flight controls, nacelles), new avionics and custom interior and paint.

Another recently completed Twin Otter is the DHC-6-200HG, which upgrades a -100 or -200 Twin Otter to the -300 configuration and performance, but with a lighter empty weight. The -200HG includes new Pratt & Whitney Canada PT6A-27 engines approved for 620-shp operation and a maximum takeoff weight of 12,500 pounds, up from 11,579. For even greater load-carrying capability, Ikhana offers the -300RG and -400RG mods, with maximum takeoff and landing weight increased to 14,000 pounds.

These upgraded Twin Otters are aimed at restricted category authorization special purpose-type operations such as forest and wildlife conservation, aerial survey, patrolling, weather control, cargo and search-and-rescue. But for added convenience, these models can operate under dual standard or restricted category FAA airworthiness certificates.

Vancouver-based Harbour Air Group operates two -200HGs, which it purchased in 2012. “The modification allows for a greater payload than a comparable DHC-6-300 series,” said president Peter Evans, “which translates into added capacity and increased passenger loads. We like investments that allow us to carry more revenue-paying passengers on the same aircraft, it makes good business sense.”

Another Canadian operator, G-Sky Aviation of Fort McMurray, Alberta, flies a -200HG on charters in the Alberta oil sands region. “With all my years in the operation of Twin Otters, I can say that Ikhana’s DHC-6-200HG is a brilliant example of how the aircraft should be configured to maximize its potential,” said Bill Houghton, general manager of operations.

http://www.ainonline.com/aviation-news/ ... ive-longer

Greenland Air was the only commercial operator I knew that had the gross weight of 14500 approved for scheduled flight -- no increase in zero fuel weight -- MNR in Ontario certified to 14500 for water bombing -- this is all 300 a\c and of course ferry up to 18000 -- so structural limits seem to not be as limiting for 300 series aircraft as licensing in Canada

Twin otters don't have a zero fuel weight