To P or not to P, that is the question

[Dave Underwood]

I have operated a P337 now for 10 years now. Yes, you are limited to 5 seats, but as anyone will tell you, the 337 is really a four seater carrying a tonne of luggage. The rear seats are very small and not easy to get into. Kiddi seats at best. I have never installed the 5th seat and save on the insurance.

As for maintenance, not much real difference in equipment from a T. You have a pair of dump valves on the rear fire wall and an altitude controller. As there were smokers in my plane at one point, I had to have the dump valves overhauled early in my ownership. You also do have a door seal which can be an issue. Replacements are expensive. I have considered an inflatable seal, but the beer budget always gets spent on something else.

If the aircraft does not pressurize, you are in for a bit of an voyage of discovery to find all the leaks. Once done, everything remains stable. Finding the leaks and fixing them all may take a bit of time. If you can find a place with the right equipment and experience, the challenge is reduced. We have used a leaf blower with much success. You can hear most leaks.

One thing as it is a pressure hull is that any holes, for say a new antenna or GPS require a DER approval with hoop stresses being a concern. That means a doubler plate and enough rivets of the right strength. There are many DER's, but you might want to search for references on this site for Ray Torres of RT Aerospace.

Some of the systems are slightly different, but not a major deal.

Flying is no different from other 337's I have flown. That said, it is very nice to be in cruise at say 18 k, above all the traffic and weather, but not wearing a nose bag. ATC also treat you differently in the high altitude sectors, the exception being they might think you are a turbine, but you're not.

The one consideration is to always be thinking about the decent profile. At 1000 fpm from 18 k to say sea level is 18 minutes and if you are doing 180 kts plus on the decent you need to start a long way back - 3x18 nm. If you take slow rate, even further out.

There are a few training considerations. Emergency decent being one, but it is all pretty well spelt out in the POH. You don't need a high altitude endorcement, but as you are approaching the danger zone above 18k, it might not be a bad idea, though not required until you are flying over 25k.

They are a great IFR machine when equiped.

Hope that helps. Let me know if you have any other questions.

Regards - Dave

[Flyer22]

Thanks for the reply. I flew cargo and pax over the Rockies for a 135 operation in some (unpressurized) Navajo's, so I am familiar with trying to go down and slow down without shock cooling, as well as operating with oxygen.

I am also hoping to find a 337 w/ Gami injectors and run LOP. It seems like I should be able to fly 1000nm in the high teenes with a bit of tailwind if I have an aircraft w/ the long range fuel option.

I am sold on inline thrust and turbocharging for my family missions out of Denver, and yes, the 5th seat is for future kid.

Do you think that you have higher insurance rates with the pressurization than without?

Are there any required annual recurrent training requirements that you don't see with an unpressurized 337?

Thanks

[Dave Underwood]

I run GAMI's and although it does help to lower consumption a bit when LOP, I still use a range limitation of about 800 to 850 nm. My age I guess. I also like to always have at least an hour in the tanks or more when I land. Age again.

On cooling, I always try for no faster than 2 " a minute on decent, but you have had that experience with the Navajo. I think it is all about decent planning and telling ATC what you want and when you want it by.

On insurance, you would have to check with your supplier. Here in the UK it does not seem to make any difference. I'm paying about the same as a T337 based on discussion. Again insurance is different here. I suggest you shop around. There is one broker who specialises in 337's who's rate were ok in the past and also offered pretty good service, but also try Avemco as well.

There was another thread on insurance costs - suggest you search.

On training, I would suggest you spend some time flying with someone familar with flight in the high teens. It is different and you do need to be thinking about how to quickly loose 6 to 8 thousand feet with out bending the plane but staying awake at the same time. I am ok up to about 15 k feet as a non-smoker who would claim to be fit (ok I am big build) and have skied that high with out problems after the second day.

Recurrent training in my experience does not cover pressurised flight, more standard procedures on the 337. I did RTC for my initial training and they were pretty good as John had a 337 at the time.

As I suggested earlier, although not required, get a high altitude endorsement and I woudl think the insurance folks would be happy. It also gives you the knowledge & understanding of both the flight and human issues.

I view having a P the same as having A/C in my car 20 years ago. As soon as I had experienced it I would find it very hard to buy a car with out it. That said, I also occasionally fly non-pressurised aircraft and it is no big deal either way.

On long legs, I always find higher has less turbulence and less traffic, more directs and you are above most weather.

I would suggest if you are looking for a P to get one with de-ice as it does make the decent through ice layers a little more comfortable. That said, the plane will still fly with a lot of ice, but then again, you are a test pilot with no control over the conditions.

Hope that assists.

Blue Skies - Dave

[Dave Underwood]

In the above post, please translate all occurances of "decent" as "descent".

OK, all decent descents are great. Too late and too tired..

Dave

[hharney]

I just have to pipe in on this discussion too. I think this topic deserves more input around the camping environment at Sun N' Fun. You should plan to come out and actually kick the tires of all these models. SOAPA is counting on having at least one of each for those interested parties to be able to stroke these birds in person. Just a suggestion.

As for me on this topic, I always say "what is the mission"? If it is high altitude MEA's and longer distance flights then the P model might be warranted. I flew in the mountains for the first 20 years of my piloting hobby. Only had the privilege of turbos (C320) with one of 4 aircraft that I had some time in. The Skymaster's were all normal and typically flying in the low to mid teens for most cross country flights. I flew very little IFR then so MEA's were usually not in the picture. But if a person was flying IFR, in the west, over the mountains, the P model might make better sense. Now a resident of the mid west flat lands, a P model really doesn't compute for me. I typically always file for cross country now but the MEA's are below 10K. From 8-10K is the normal Skymaster's best friend. I can say that turbos and pressurization would be nice but there has only been maybe a handful of times that I really needed it. When comes to maintenance I am really glad I have the normal. My IA is too. He works on both and the normal does make life a lot easier. Skymaster is a great airplane, whether it's a P model or just the normal depends on the type of mission you are going to use it for. Most of my flying is just recreational and maybe a half dozen long flights a year. I really like the performance that I have with the lighter weight for the type of flying that I do. I enjoy unimproved strips, back country and weekend warrior flying.

Coming to Sun N' Fun this April will give a great opportunity to see aircraft and talk to the pilots. A huge advantage before you buy. Be careful out there because the Skymaster has been known to have a fair share of ramp queens. A good thorough pre-buy is a must. Make sure you select the inspector that is familiar with Skymasters but not the specific plane you are inspecting. You probably know this routine, good luck and hope to see you in Lakeland.