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Is the Jetprop the right plane for my mission? (and other high performance types)

Cessna P210/SE/337 Prez’d, CHAPTER THREE: GRASS

Well by definition in the OP we are talking heavyish aircraft here, so neither of them perfect for grass.
Not being a grass expert myself, I do have my share of grass operations and I think the key elements are:

-Propeller clearance
-T/O and LDG speeds
-LDG design
-Tyre size and pressure

In general 210’s seem to do reasonably well on grass, but I will explain better:

Prop clearance on P210 is medium. Two important factors are CG/weight and nose strut. The 210’s CG range is big so you are better off in the aft half of the range and then prop clearance is much less of an issue. Fortunately when loading the aircraft you tend to put weight aft. I have an aft fuel tank which I use to modulate CG position for occasions like this, so when taxiing over bumpy grass it is easier to keep the prop well clear.
Also nose strut servicing is critical. Not that it is any more difficult than any other aircraft: it is just a heavy nose with an empty aircraft and if not properly serviced, then the propeller may get closer to ground or your nose may be bouncier. It is not just the correct amount of gas: also hydraulic fluid. Again no different from other aircraft just more critical if you taxi on grass.

The SE has different props available but do not know if prop clearance is better or worse than piston P210, but I knwo quite a few operators use it regularly on grass.

T/O and T/D speeds are reasonable at around 70/ 65 KTS.

210 LDG design seems to work well on grass too. Discussed above on the nose strut. There is one SB to replace the NLG trunnion to avoid cracks, but no correlation has been found between cracked units and grass operation. Thoughts are along misrigging of retraction system and tow-tug misuse (over-turn). Unloading it as proposed with aft CG and yoke during taxi should be enough, but some aircraft in the field have been modified with the improved trunnion. The mains are simply sprung by a steel leg. Many 210’s are operated on grass/dirt frequently, just search the web. The only caveat is you must start-off with a properly set system so there are no undue plays/damages in the locking mechanisms. If there is play, then the vibrational loads of grass taxiing could eventually damage parts. I am not aware of someone having reported it. I would suggest verifying yours for solid saddle blocks and shells before flying regularly on grass. If so, it is as robust as a retractable will be on grass.There is also an inspection on the steel legs to ensure they have no corrosion. Like most landing gear, the legs are subjected to strikes from runway gravel, which will remove paint and if left unwatched for years can cause corrosion: better keep it clean. I know one 210 had its MLG leg cracked through at a heavy corrosion pit, but it does not seem to be a fleet issue.

On tyre size and press the mains on the 210 are standard 6.00-6 but pressure is quite low at 55psi. This is good and I have found grass behaviour is better than the much lighter 177RG I used to fly at the same grass airfields with higher tyre pressures and smaller tyres, although not as good as the much lighter C172.

Tyre pressure, rather than weight, is what will determine how deep it goes into the ground. For the same depth, wheel diameter (the bigger the better) and weight will determine how difficult it is to get out of it.

I would say the P210 is good for grass if not ideal, but beware that you will have to move a 4000lbs airplane if it sinks its way into the mud. Rather than using lots of power, after parking for a few days on grass, two adults pushing on top of the main wheels to move it out of the pits before start up has always been enough for me.

As the the 337, I have not flown it on grass.However based on the lighter nose, lower speeds on our STOL version, higher propeller clearance (if necessary you can even taxi with the front engine stopped and the rear engine is really high) and reports from other operators, it is probably one of the best if not the best grass-field capable piston twin (and definitely the best pressurized one). Same concern as to clean, rigged LDG as P210 applies.
I can only guess on the non-STOL version but it does have the same stall speeds as the P210 at MLW, so I expect similar characteristics.
Again we are talking a heavy airplane here so if you do have to get it out of the mud, it is no mean feat!

While PA46’s can be operated on grass, the experience does not seem to be as widespread as 210’s and 337’s and the low-wing and LDG design makes for more mud in the wells…. It can be done, but my impression is that it is not ideal.

Last Edited by Antonio at 11 Jan 21:04
Antonio
LESB, Spain

HBadger wrote:

Thanks for everyone’s input.

I was briefly considering the MU2 and it is somewhat of a dream, but realistically I think it is too much plane for me to handle. I don’t fly enough. Other twins might be more forgiving but then the MTOW issue comes up again.

Here I go again sounding like a broken record :

You need a Turbo Commander 690A/B. It can do everything you need, it’s very forgiving to fly and compared to many turbines, reasonably cheap to maintain (MU-2’s are very well built and capable, too, but they’re less forgiving). It’s big MLG tyres eat grass and gravel for lunch and they’re short field planes. There’s a reason every drug smuggler uses them.. Before you dismiss a turbine twin out of hand, consider that the TPE’s are about half as much to operate as PT6’s, so in reality, the engine cost is almost a wash compared to a single.



Last Edited by AdamFrisch at 13 Jan 04:31

@AdamFrisch always great to see a 690 video posted. EASA requires a type rating with annual revalidation, and while I believe there are work arounds (in the aircraft with the local regulator approval), it has to be in an approved simulator. These are getting more expensive every year, and given the small population of 690 types in Europe, it must make the practicalities of revalidation a bit of a challenge.

Nearly all grown up multi engine types publish ASDR, and while the 690 is not performance A, it does publish ASDR tables in the POH. If ASDR is published, it is a performance limitation. The OP is looking to use 600m grass airfield, now a very skinny crew on Jet A1 fumes might find the 690 ASDR table can be quite short, I doubt it goes down to 600 m on non tarmac.

Oxford (EGTK), United Kingdom

RobertL18C wrote:

f ASDR is published, it is a performance limitation.

Under what rule?

Biggin Hill

I believe it is one of the reasons the DA42 may have not published it. Probably under the general flight preparation due care rules, certainly on an exam flight if there is an ASDA table you need to show compliance, even if it is a performance B aircraft. As there is no concept of V1 in Performance B it is somewhat theoretical. FAA part 135 would require it, and no doubt AOC OM would as well.

The PC12 publishes an accelerate stop table, which arguably means operating from Denham is a challenge on a long sector in the summer.

Oxford (EGTK), United Kingdom

Sebastian_G wrote:

Probably such a plane could even be built. Like a baby PC12 or a PA46 with new landing gear and bigger flaps.

A “baby PC12” would be an awesome aircraft which I would want. Of course, I already want a PC12. but I am so far financially removed from the possibility of owning or even renting one – it’s a shame.

Low-hours pilot
EDVM Hildesheim, Germany

MedEwok wrote:

Like a baby PC12 or a PA46 with new landing gear and bigger flaps

Something close already exists and is called Silver Eagle

Antonio
LESB, Spain

AdamFrisch wrote:

You need a Turbo Commander 690A/B. It can do everything you need, it’s very forgiving to fly and compared to many turbines, reasonably cheap to maintain (MU-2’s are very well built and capable, too, but they’re less forgiving). It’s big MLG tyres eat grass and gravel for lunch and they’re short field planes. There’s a reason every drug smuggler uses them.. Before you dismiss a turbine twin out of hand, consider that the TPE’s are about half as much to operate as PT6’s, so in reality, the engine cost is almost a wash compared to a single.

We used to run two 690A’s on an AOC operation in the mid-1990’s. Everybody loved them and engine costs were way under the B200’s next door…until one of our pilots made a mistake on a startup.

Try to startup a PT6 on a low battery (having to turn only the HP spool) and you will get away with it, try it on a TPE331 (having to turn high and low-pressure as well as propeller) and you’ll get a $150k invoice.

690’s are robust and capable aircraft, but beyond what has been said, in EASA-land private operations, they fall under the NCC banner (vs NCO) making them a pain in the butt.

Antonio
LESB, Spain

RobertL18C wrote:

Probably under the general flight preparation due care rules, certainly on an exam flight if there is an ASDA table you need to show compliance, even if it is a performance B aircraft. As there is no concept of V1 in Performance B it is somewhat theoretical. FAA part 135 would require it, and no doubt AOC OM would as well.

Are you sure this is required under part-NCO? As far as I can see, part-NCO doesn’t even have specific requirements for TODA and LDA — only very general rules like

NCO.OP.100 Use of aerodromes and operating sites
The pilot-in-command shall only use aerodromes and operating sites that are adequate for the type of aircraft and operation concerned

NCO.POL.110 Performance—general
The pilot-in-command shall only operate the aircraft if the performance is adequate to comply with the applicable rules of the air and any other restrictions applicable to the flight, the airspace or the aerodromes or operating sites used, taking into account the charting accuracy of any charts and maps used

Last Edited by Airborne_Again at 13 Jan 13:05
ESKC (Uppsala/Sundbro), Sweden

Airborne_Again wrote:

Are you sure this is required under part-NCO?

Can one operate TC690 under NCO?

Germany
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