To P or not to P, that is the question
 

I am looking into the various costs of owning and operating a 337. I am currently in a toss up between a P337 and unpressurized, T337.

The pros of pressurization are obvious, while the advantages of unpressurized aircraft, other than costs, seem to be in the higher certified service ceiling, ability to seat 6, and possibly more interior space. Can anyone verify?

Can anyone quantify the additional costs of operating a pressurized Skymaster such as maintenance, training, and insurance?

Thanks

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

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

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

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

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

Dave

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.

flyer22
That is a great Idea for you to go to sun and fun your see all kinds get lots of ideas.
I fly p337 back and forth across the country at least once or twice a year and into the bahamas and the other islands. I fly at 16k one way and 17k the other and it works great. only diferance would be if the winds are crazy and Then I go down and get below the teens. I fly out of Montana and the p337 is the ticket to get out of the mountains and go down the the road. The p337 is also great for low alt and sight seeing. There is no problem of getting down, is just and matter of droping the gear and one notch of flaps great speed breaks. See you at sun and fun N268 Yvonne and DAve

I have had my 73 P337 for just a year but really like the plane. MOst of my flying is out west and VFR through the mountains, but spending a lot of time where traffic might be a problem.

I just hate to reply to ATC with "no joy" and that is one of the important benefits of my P model. Normally I climb quickly to 13.500 or 14,500 and my cabin pressure doesn't get much over 9,000 ft. At those altitudes you just don't find a lot of traffic as the turbine boys are way above and the NA ones are well below.

Having the 5th seat works out OK for me as I have three small kids. However I have ordered the cargo pod from RT Aerospace for a more comfortable cabin.


Dave Dillehay
N84E

Thanks for the great replies.

I think a trip to SnF would be a must before I buy, although I probably will not get out there this year.

My typical mission is Denver to Atlanta, just about 1000nm on the dot, and I would like to make it eastbound non-stop. That means high altitudes for both fuel efficiency and tailwinds, as well as LOP operation. Other missions include the Bahamas and some westbound travel from Denver, as well as "flightseeing".

As Denver residents we are acclimatized to 5000ft, and frequently drive/hike/bike/ski above 10,000 ft with no ill effects, which is not the case for people who reside at sea level. Therefore, we are a little more capable of hanging out at high altitudes, be that 12k w/o pressurization, or 20k w/ cabin pressurized to 10k as would be the case with a P337.

I guess I am just trying to figure out the maintenance and insurance hits. So far, from your inputs, they don't seem to be showstoppers.

good luck on 1000 mile legs I have140 gal plus and I plan on 190Knts . I thinks if you have a little wind or or if you use less than 30 gal per hr. you won't get the speed. you figure it out. If you can plan on 1000 per leg you will land short. I plan on three to three and one half hour flight are just fine with me and then I have lots of fuel to if things go sideways.

To "P" or not to "P", that is the question
 

Very interesting thread, to all that's been said; as the owner of P337H, N64N I would add the following: It's an ideal aircraft for the mission that you describe but I do agree that thousand mile legs will put you at the limit of range. Certainly beyond my comfort level, but that's an age thing as someone commented.
Except for anything requiring penetrating the pressure hull, the pressurization adds little in terms of maintenance. The systems are small and I have found them to be very reliable. If you need to penetrate the hull, that's a whole new challenge, both to reseal if you are going through an existing opening or to go through the DER process if you are adding something like an antenna.
That said, I have found maintenance on the P's to be substantially more complicated than on a normally aspirated 337. I am an A&P/IA and do my own work and the engine compartments are crowded, almost nothing can be accomplished without removing other components and systems which, of course need to be reinstalled, but wait, while its out let's inspect and repair. A friend once remarked that the P337 has all the systems of a King Air without the room to work. It helps to be a watchmaker with the arms of a Chimpanzee to get in there and do stuff.
The pressurization system makes the aircraft very warm, hot in fact. You are sealed in this capsule and the compressed air from the pressurization is hot until you get to altitude. May not be a big problem in Denver, but it is in Phoenix where I fly. Once you are at altitude, it can get cold so a properly working heater is a must. The Janitrol heaters are another system that requires maintenance and is subject to an AD. No big deal but just one more system that requires maintenance and takes up front engine compartment space.
Insurance is a giant pain in the butt. Insurance companies must think that this is some kind of mini-airliner because they insist on recurrent training and the premiums are very costly, much more so than a non-"P". There is another thread that talks about this.
All that said, the P Skymaster is a fantastic aircraft. Great performance in a small package, relatively economical to own and fly. My recommendation is to find an A&P/IA who knows the plane to do a thorough pre-buy and to do your maintenance. Also consider attending a CPA 337 systems and procedures course, very valuable.
Best to you

The first P models had 128 gal and the newer ones 146gal Correct me if I am wrong. We had a 73P Flew form Vancouver Island to Reno / Reno to Pheonix We had to really watch fuel on the first leg with a head wind. If you are planning longer trips I would go for the larger tanks.

I'm resurrecting this thread because it's the exact question I have. I'm a potential P337 buyer, but probably not until later next year. The reason I'm asking now is that I can make it to Groton, but if I decide not to get a P337 there are a few other unpressurized planes that I might choose over the 337 and attending this year becomes less of a priority.

Some of the reasons I think I need a P337:
I frequently visit short strips (2200' paved with no obstructions, 2500' paved with trees one end, 2900' grass w/ no trees - all less than 1000'MSL elevation.) The bulk of my flying is north of 40deg latitude. I have a 4x/year route that goes south around/thru JFK/LGA, PHL, BWI and DCA and the deviations I get are horrendous. From what I've heard if I can get to 15K or higher I'll get much straighter routing. I've been routed over 150nm off course in a single flight. I won't go out over the water in my single and it does poorly above 12,000'. I'm also sick of picking my way through local summer weather at 9,000-11,000 ft. My wife gets headaches if not on O2 above 10-12K and neither of us are fans of the nosebag.

So onto my specific questions. I have searched the site and read 100's of messages, but I still have an unanswered question or two:

1) Re: Cabin temp with pressurization. Can you turn off the pressurization until you're at altitude to keep incoming fresh air temps down? Can you bypass the pressurization intake and get direct fresh air? If so, is there any problem with turning pressurization on suddenly at altitude? If not, how much above outside air temp do you see the cabin temps during climbout?

2) How much do the intercoolers help with incoming cabin air temps? If you can estimate an actual temperature diff in degrees F that would be great.

3) If you have a P337, what's your actual empty weight? What have you added that bumped it up significantly? What's the lowest empty weight I'm going to realistically find on a P337 without AC?

4) What are the differences between the 73-77 T337G (I think this is the official Cessna code for the early pressurized aircraft) and the 78-80 P337H? For some reason this is tough to find. It's often listed as "minor changes." I have found differences by manufacturing year (seat rails, tanks) but not by model letter.

So, please - talk me out of a pressurized plane!

Thanks for your help,

Jim C

No replies? Was it too many questions?

Let's just try one line of questioning:

How much does your Turbo or Pressurized 337 actually weigh empty? What's the gross? What's your year & model?

I can find the book figures; I'm interested in real-world answers. I have yet to fly a plane from any manufacturer that's actually as light as the factory numbers.

A reply
 

I will be back in my office in the next day or two and will pull my latest wt & bal and have a look at my various manuals to try and answer some of your questions.

D

1) Re: Cabin temp with pressurization. Can you turn off the pressurization until you're at altitude to keep incoming fresh air temps down? Can you bypass the pressurization intake and get direct fresh air? If so, is there any problem with turning pressurization on suddenly at altitude? If not, how much above outside air temp do you see the cabin temps during climbout?

Yes, you can turn on pressurization in flight. I wish my 73 T337G Pressurized had AC though. It can get warm at takeoff and landing. It is fine up high. I may try one of those ice coolers.

2) How much do the intercoolers help with incoming cabin air temps? If you can estimate an actual temperature diff in degrees F that would be great.

I don't know, I do not have an IC

3) If you have a P337, what's your actual empty weight? What have you added that bumped it up significantly? What's the lowest empty weight I'm going to realistically find on a P337 without AC?

3172.7 is my empty weight. Full of gas that leaves about 735lb for max takeoff, but landing weight is lower. Also, you have to be inside the arm/moment envelope, which makes it tough to actually use all of that weight.

4) What are the differences between the 73-77 T337G (I think this is the official Cessna code for the early pressurized aircraft) and the 78-80 P337H? For some reason this is tough to find. It's often listed as "minor changes." I have found differences by manufacturing year (seat rails, tanks) but not by model letter.

I have a 73 T337G. I am not sure what the changes are.

bj,

Can I bother you with a few followup questions?

re: Warm during takeoff and landing - What's your latitude where you're based? Where do you do most of your flying?

re: tough to use all 735lb - Do you usually find yourself too far forward or aft of the cg?

Does anyone know if the cg location of the earlier long range tanks is about the same as the later 148 gallon tanks?

Thanks,

Jim

Jim,
No problem at all. We are based in Michigan. Today we flew from STL to ARB in MI. It was 90 - 95F at both airports. Passengers were sweating on takeoff and landing, but very comfortable at 17,500 where we were cruising with a ground speed of 215-220. Whole trip was just under 2 hours, something that few light twins can do.

The heat is my only complaint, and we're going to order one of those ice coolers next week to make things better. I haven't had the plane long enough to know how it is during winter, but I suspect it will be MUCH better.

For the CG, it's always near the forward edge. But then again I am 6'5 and my instructor is also 6'. Plus we are always flying with full tanks.

I spent a lot of time looking, it's hard to beat this without spending a lot more on the plane and gas.

BJ, keep us posted as to your purchase of a "cooler" for your P337G and how it performs. We also have a 73 P337G and have been considering the same purchase.

JB

It seems that a large winter Arctic Air setup weighs about the same (67lbs) as factory A/C. It can be removed when you want the space & weight in winter, but it also needs to be refilled.

For those of you considering the Arctic Air coolers - do you wish you had factory A/C?

http://www.arcticaircooler.com/

You might want to price the Riley air conditioner...I don't know about the cost but it works great.

My 2 cents on the Arctic Air (cooler) air conditioner... I purchased one of the larger ones at Oshkosh a few years ago. It works as advertised, which is to say it does a good job keeping the cabin cool.

The preparation work is the problem. Stopping at the gas station on the way to the airport to buy several large bags of ice, getting it all loaded, lifting 50+ pounds into a sweltering C337 cabin and securing it, and by now one is totally drenched in sweat. Not fun.

Realistically about 45 minutes to an hour of cool air is what you get with my unit. Which will get you up and down assuming it is turned off at altitude. If you have a multi-leg day, a re-load is necessary assuming you can get the ice at the airport you happen to be at and then you get to enjoy that preparation work once again.

I try very hard not to use my unit because of all this and actually have not used it in 2 or 3 years now. If I was really motivated for a particular flight and it was 95 plus degrees, I would probably use it but generally if it is that warm outside, I try to avoid flying. You may not have that option however, so the prep work may be worth it to you.

Good Luck,
Ed

Ed. Is there a reason that you don't pump the water out of your Arctic Air and leave the unit in the Plane?

I talked with the people form Arctic Air and they said that if you use block ice you can achieve a longer cooling period. For other purposes we have used frozen water in gallon milk jugs and am considering this if we purchase an Arctic Air unit.

JB

I suppose not any real reason. I guess it seemed less messy to do the prep work outside the airplane. Otherwise, one would be on his knees dragging dripping bags of ice into the back of the airplane to load the cooler. My airplane is a 73G model with no baggage door. So that means unlatching and raising the bench seat to gain access to the back of the cabin to reach the unit. I do admit to being a bit of a "neat freak." I do not care for clutter in my airplane so if I am not to use the unit, then I do not want it sitting in the plane. It takes up a a fair amount of space back there and is an "eye sore."

Just keep in mind, that the unit requires preparation and that preparation is going to be accomplished one way or the other in 90+ degree heat. Once the work is done, the unit will work as advertised.

Ed

A few more answers
 

The following is what I know, clearly subject to the idiosyncrasies of specific aircraft:

Some of the reasons I think I need a P337:
I frequently visit short strips (2200' paved with no obstructions, 2500' paved with trees one end, 2900' grass w/ no trees - all less than 1000'MSL elevation.) The bulk of my flying is north of 40deg latitude. I have a 4x/year route that goes south around/thru JFK/LGA, PHL, BWI and DCA and the deviations I get are horrendous. From what I've heard if I can get to 15K or higher I'll get much straighter routing. I've been routed over 150nm off course in a single flight. I won't go out over the water in my single and it does poorly above 12,000'. I'm also sick of picking my way through local summer weather at 9,000-11,000 ft. My wife gets headaches if not on O2 above 10-12K and neither of us are fans of the nosebag.

a) The T and P will give you pretty good performance in and out of short fields. My aircraft is an 1978 FT337GP. The F denotes it was built by Reims and the P denotes is it pressurised. It is a Skymaster II. I am pretty sure the difference between the Skymaster and the II related to equipment. Mine as a II has a full deice, a 400-A Integrated Flight Control System/autopilot, Flight Director, HIS etc.

b) The aircraft is a bit heavy for softer grass fields as you might leave ruts in places. That said, I go in and out of several that are in your length range and shorter without difficulty. Just remember soft field technique. On pavement, the aircraft is great.

c) From my manual, the following are the short field take-off distances listed:

Short Field take-off, paved runway, SL, 20°C, no wind, 1/3 flaps, 2800 rpm, 37 inches, mixtures rich, cowl flaps open
at 4700 lbs – ground roll of 985’ and 1565’ to clear 50 ‘. That was in a new aircraft with perfect technique so add say 20% for margin.
at 4400 lbs – gnd roll of 845’/1345 to clear 50’ plus 20%
The manual suggests adding 15% to the ground rolls if operating on grass. For additional margin make it 25%. Still a very reasonable performer.
The manual also says you can decreases the above figures by 10% for each 11 knots of headwind.

d) On pressurised flight, my experience is that as soon as you are above about 14 or 15 k, you are generally controlled by the high altitude sectors. You are treated differently and direct routing is frequent when you are above 14 k. You certainly don’t get messed around as do when you are at say 6 k trying to go through Boston for example. I always file IFR which also makes a difference. My view is that you are above the rest of the GA folks above 14 k and below the airline traffic so it is pretty quiet territory.

e) The weather above 14 k is still an issue, but sometimes you can see more and TCU avoidance at pilots discretion is always given. A storm scope or radar is mandatory in my view if you intend to fly on those rougher days. I have a storm scope and always get deviations when requested. When things are really bad TCU wise, either don’t fly or go low and stay well clear of rain shafts. I have done trips in the mid-teens, in solid clag with embeddeds and when they are wide apart, no real problem as with the StormScope and a little help from the controllers you can get around them. When they a close together, you do have that butt clenching “I really wish I was somewhere else” moment.

f) 337’s are easy twins so water crossings are much less of an issue.

g) So onto my specific questions. I have searched the site and read 100's of messages, but I still have an unanswered question or two:

1) Re: Cabin temp with pressurization. Can you turn off the pressurization until you're at altitude to keep incoming fresh air temps down? Yes you can turn the pressurisation off, but all that really does is fully open the dump valve on the rear firewall, which does increase the cabin air flow a bit, but won't stop the flow from the pressurisation system. You can direct the incoming airflow off the turbo through its own inter cooler which does help, not much on the ground, but once going, a lot. The way the system work, which makes it fool proof is air flow from the high pressure side of the turbo goes up and over the rear portion of the front engine through a restrictor which controls how much air is taken from the engine side. It then either goes via its inter-cooler or directly in to the cabin air systems by way of the heater and a fan mounted on the firewall. The control is via a pair of dump valves on the rear firewall, one controlled by the on/off switch and the other as the failsafe at 3.35 psi. So sometimes it might feel a bit warm, but generally not bad. I’ve never found the inlet air that warm flying here in the UK, but things are generally cool here. On a hot Florida day, I open the windows and/or leave the upper door open. OK, it might be a bit warm, but as soon as you get airborne, things cool down quite nicely. You can then close the windows and get the pressurisation running.

Can you bypass the pressurization intake and get direct fresh air? No, just by directing airflow through the intercooler is my opinion. OK, you could pull out both dump valves which shuts off all airflow at the firewall, but I figure just having the storm windows open is just as good.

If so, is there any problem with turning pressurization on suddenly at altitude? Yes, it is quite hard on the ears as the plane pressurises up quite quickly. I suppose you could set the altitude controller up high and then crank it down which would be less painful on the ears. That said, I fly with the pressurisation running all the time as it give a more pleasant flight. Buzzing along at 8 k with a 3 or 4 k cabin is nice in my view.

If not, how much above outside air temp do you see the cabin temps during climb-out? Negligible to only slightly warmer once you are airborne. Never measured it.

2) How much do the intercoolers help with incoming cabin air temps? If you can estimate an actual temperature diff in degrees F that would be great.
There are already intercoolers in the cabin inlet air circuit which is really only effective when you are airborne, but an additional intercooler just off the turbo is available as an STC’d unit and I assume that is what you are referring to. Those intercoolers I believe give you about a 6 to 10 degree C drop, but you would have to check with the suppliers for the exact drop and how much you would get at low speeds. I never fancied the additional air scoop. That drop when combined with the drop you get across the cabin air intercooler would be quite significant I would imagine, but only once you are airborne and have good flow through the intercoolers.

3) If you have a P337, what's your actual empty weight? The book empty weight is 3061 lbs for a Skymaster and 3167 lbs for a Skymaster II and the gross weight is 4700 lbs for take-off and 4465 lbs for landing. Mine actually weighs in at 3361 lbs empty, well, as empty as I normally treat it with survival gear, raft etc.

What have you added that bumped it up significantly? There are two or three layers of paint on my aircraft, measuring some 70 plus microns thick. I figure that is where the majority of weight has come from. The Garmin stack is likely a bit lighter than the original ARC Radios, but I also have an ADF, EDM760 and the Stormscope plus some extra antennas and always carry survival gear. The last time it was weighed, the fellow suggested the majority was extra paint, so one day perhaps a strip and repaint will be in order.

What's the lowest empty weight I'm going to realistically find on a P337 without AC? Going to depend on the plane and layers of paint.

What’s the reality? You can carry up to 888 lbs of fuel or with less fuel, almost anything that you can fit in the cabin. With full fuel, I can still carry 451 lbs of me and other stuff. That work great for me.

4) What are the differences between the 73-77 T337G (I think this is the official Cessna code for the early pressurized aircraft) and the 78-80 P337H? For some reason this is tough to find. It's often listed as "minor changes." I have found differences by manufacturing year (seat rails, tanks) but not by model letter.

My parts manual covers all pressurized Skymaster aircraft built from 1973 to 1980. I think the serial numbers tell the story as they are continuous through the entire production run starting in 1973 with serial number P3370001 and going to 1980 with serial number P3370342 which was the final H built. There were not a huge number of big changes through the entire build, but you would have to go and have a good look at the parts manual to confirm that for yourself. The increase in fuel capacity to 148 gals was a good change, but from memory and having just had a fast look, there are not big differences between serial numbers. Lots of small differences, yes, but the basic aircraft is much the same.


I hope that gives you a bit more information.

Blue skies - Dave

Dave,

Thanks very much for the very thorough answer!

The weight on this particular grass strip shouldn't be a problem, as it's home to a Baron that flies out 2-3 days a week. Immediately after a soaking rain is an issue, of course, but under normal conditions it's solid - I've walked it.

I fly IFR on any trips through busy airspace and get screwed on the east coast anywhere from NYC to the DC area and everywhere in between. I can't remember the last time I flew the full north-south roundtrip without a "stand by to copy amended clearance" at least once.

North of the Massachusetts line, deviations are always given and "cleared direct" is common. On some legs I get handed off to center as low as 7K where there isn't any local approach radar. One other advantage that I just thought of for the P/T model is the MOAs - the local ones go to 17,999. 16K would get me above the bulk of the non-frontal weather as a lot of it is rising off the mountains and doesn't go much over 14K except on the warmest days. 18K gets me above that and all the local MOAs. I'd at least be able to go between some very large gaps in the buildups most days. At the 9-11K altitudes I fly today, I often have to punch through the weakest spot I can find in the late afternoon and fly the long way around the MOAs. I fly with both ADS & XM weather but have had them both fail simultaneously & would like to have onboard radar, although I consider it a luxury.

I will have to get used to the reduced seating & payload, but for most of my trips it won't be an issue. I expect I'd try to keep it fueled at about 100 gallons, which should leave about 700-750 lbs payload and a 450-500nm range - good for 90% of my trips.

Jim

I would suggest that you read these posts from Dennis Hamblin of Flint Fuel Tanks. There is a post that describes the differences in the wings of P model Skymasters.

http://www.337skymaster.com/messages...earchid=585613

Herb,

That link bring up a "Sorry - no matches" page for me. Do you have another link?

Jim

Herb, kind of off subject but do you know of the feasibility of converting the rear seats of a 73 P model from fixed position to sliders?

JB

Try this and click "find all posts by ....."

http://www.337skymaster.com/messages/member.php?u=13445

Sorry James I do not. It sounds like it would require a field approval. It may not be impossible because the P model had the slider seat later in the manufacturing run. Not sure if the H model was the first or if there were G models with the slider?

Good Luck

I think the slider seat started in the '75 P models. My '77 had it. The fuel tanks also changed in the '75 models with long range fuel going to 148 gallons, no tank switching except to cross feed.

Thanks Jeff, I need to find someone that has installed later model rear seats in a 1973 P model to establish whether it is possible.

JB

Found it, for those interested in reading the spar construction info..

http://www.337skymaster.com/messages...2&postcount=31