Engine Misfire at Altitude.

[mshac]

Originally Posted by JimC

ALL aircraft with a ceiling above FL250 require the endorsement. The FARs define a "pressurized aircraft" as an aircraft with a ceiling higher than 25,000 ft. That means all T337s, period.

I'm still getting the misfiring...haven't fixed it yet. Kim, do you still have all that pressurize mag hardware?

Nope, that's wrong. From the FAA's own Advisory Circular: "As required by 14 CFR § 61.31, pilots who fly at altitudes at or above FL250 in a pressurized aircraft must receive training in the critical factors relating to safe flight operations under those circumstances."

Link: https://www.faa.gov/documentLibrary/...AC_61-107B.pdf

[JimC]

I'm not saying this makes sense - it's a poorly written regulation - but it's clear. The "problem" is the FAR's definition of "pressurized aircraft" - it's any aircraft that can fly over 25,000 ft. So according to 61.31(g) a T337 is a pressurized aircraft, and a P337 is not. There are many recently developed aircraft that you and I would call pressurized that have maximum operating altitudes of 25,000 ft, even though the engine and airframe can go higher. 61.31(g) does not apply to them.

The regulations make much more sense if you replace the word "pressurized" with "high altitude" all through 61.31(g) - but they're written with the word "pressurized."

The FAR is pretty straightforward and clear in the way it defines "pressurized aircraft":

61.31(g)(1): "no person may act as pilot in command of a pressurized aircraft (an aircraft that has a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet MSL), unless that person has received and logged ground training from an authorized instructor and obtained an endorsement in the person's logbook"

A T337 has a service ceiling over 25,000 ft.
Therefore it is a "pressurized aircraft" according to the FARs. (Hey, I didn't say they made sense.)
Therefore all of 61.31(g) applies.
61.31(g) *never* talks about how high you are actually flying. It only talks about whether or not you're acting PIC.

BTW, the AC doesn't say that you can skip the training if you're operating below 25,000 ft. If the aircraft can go that high, you need the training.

[B2C2]

I have a 1969 T337D, non pressurized and no pressurized mags. I have tempest fine wire plugs and GAMI injectors. I have also replaced all the ignition wiring and rebuilt the magnetos. The airplane flys nicely LOP with this setup. I occasionally have experienced bumps when operating at altitude above about 17K LOP. The highest I have flown it is 21K and it was the same experience, occasional ignition bumps, but not rough operation. I have found going to ROP stops this. You don't mention if you are running LOP or ROP but you might want to see how this effects the performance.

[JimC]

I'm still ROP. I haven't upgraded *anything* yet - I don't have an engine monitor, and I have the plugs, wires & mags that came with it when I bought it 4 months ago. It does run well LOP at 13K or so.

I ran a different continental TSIO up to 25K smoothly with pressurized mags, so I know that the pressurized mags make a big difference.

PS - How do you have a 1969 T337G? The model number & year don't match.

[B2C2]

Oops, sorry its a T337D. edited my below post to reflect this

[B2C2]

I was thinking about this and was wondering how Cessna gave a service ceiling of 30K feet for the T337D. With non pressurized magnetos this seems unattainable. Did they offer these as an option on the plane when they sold it? otherwise it seems like there is no way to achieve that altitude in operation.

[Dan schultz]

Try the fine wire plugs

Dan
67S

[B2C2]

I have them. I actually have good performance up to about 19K but I have never taken it up any higher than that, Based on what i have been reading 30K feet without pressurized magnetos seems a stretch, but maybe that's not the case?

[Dan schultz]

The Piper Aerostar’s that I used to fly did fine with the fine wire plugs to 25K. We did eventually put the pressurized option on. Now this was with the 1200 series Magneto’s, which in my opinion are a better mag than the 20 series or the 6300 series Slicks.

Dan

[n86121]

In PCA above 18k ft, the world is all 090Mhz. radar, tcas, etc

That said, the heavies up there all have TCAS and can see your basic Mode AC transponder just fine.

As can FAA if within radar coverage as well.

Just remember, your 978 mhz UAT will not see any 1090 transponders directly.

You will onl see 1090 targets when both your UAT and their 1090 are observed by and within range of an ADS B ground station.

if you have dual mode 1090/978 ads B in, you will see any 1090 ads-b out aircraft, 978/1090, but not any basic 1090. mode a/c.

D

[mshac]

That's good info about UAT above 18k, but if you're that high anyway, you'll be IFR and under normal traffic separation rules, so I wouldn't be too concerned about not seeing 1090 equipped traffic. Many of us use a portable 1090/978 in unit for weather and traffic to display on our tablets, so at least there's that. I'm not familiar with "basic 1090" - I guess that would be a 1090 equipped aircraft without ADS-B? I wouldn't imagine there would be many of those around.

Fun fact - Class A airspace used to be called "Positive Control" airspace (IIRC), and it started at 24k, not 18k. So for the longest time you could fly VFR right up to 23.5k.

[n86121]

That’s right

Basic mode a/c a mode A/c transponder without ads b out.

Mode S can be selectively interrogated by radar.
Rather than just interrogating everything in sight.
But even mode S doesn’t have ads b out.

Only mode S extended squitter (ES) replaces w ads vector info.

What I’m hearing is once you get away from major metropolitan airspace,
a lot of smaller aircraft not equipping w ads b

If they don’t go into the airspace that requires it,
they don’t have to get it.

It’s a mixed blessing. Great where everyone has it,
but no guarantee one is seeing everyone else.

[mshac]

My old Bonanza had some sort of a "Transponder sniffer" traffic device that was probably from the 1980's - whenever it sensed a transponder nearby a red light flashed and there was a warning tone. It had HI-LOW sensitivity, you kept it on HI, then if you got an alert switched it to LOW. If you got another alert, you knew the other plane was closing on you. It sure did keep your head on swivel when it alerted - Good times...