Tips on flying an Arrow Turbo III?

[Daven]

Just bought a 1977 turbo arrow III with the merlyn wastegate mod and about to go fly it. Any tips on flying an Arrow III and tips with the turbo and what not? For reference my previous flying time is almost all in an Archer save a few hours in a Warrior.

 

[midlifeflyer]

I don't know the add-on wastegate, so this is from stock and may not apply. Other than the usual advice about complex transitions, the two things which stand out to me about the Turbo Arrow (loved flying them) are:

1. Watch the MP on the takeoff roll. Even with a 41" redline, it will overboost in a heartbeat. Personally, when I flew them, I felt anything more than 32" was not necessary.
2. Remember that although the Arrow doesn't qualify as high performance, the turbo makes it perform as one, with airspeeds in the 150 kt range, and a fuel flow to match if you don't pull it back in cruise. So learn how to coddle that engine in all phases of flight.

Other than those, it's just an Arrow.

 

[lsaway]

It has been many years since I sold my 77 PA28r-201T. It flies very similar to the Archer, so you should not have any difficulty flying it. It is nice to have the automatic gear extension backing you up. Maybe I was paranoid about shock cooling the engine, but power management (especially on decent) was always on top of the list. Long, shallow, high airspeed decents were my preference so I could avoid longer periods of low manifold pressure.

One other thing is to really look hard for any debris or nests in the engine compartment before every flight. I had FOD sucked into the turbo when I applied alternate air. It caused a rapid reduction in manifold pressure that fouled the plugs in flight.

 

[EdFred]

I don't know the add-on wastegate, so this is from stock and may not apply. Other than the usual advice about complex transitions, the two things which stand out to me about the Turbo Arrow (loved flying them) are:

1. Watch the MP on the takeoff roll. Even with a 41" redline, it will overboost in a heartbeat. Personally, when I flew them, I felt anything more than 32" was not necessary.
2. Remember that although the Arrow doesn't qualify as high performance, the turbo makes it perform as one, with airspeeds in the 150 kt range, and a fuel flow to match if you don't pull it back in cruise. So learn how to coddle that engine in all phases of flight.

Other than those, it's just an Arrow.

I thought the turbo arrow used the same engines as the seneca and was rated to 215hp for something like 5 minutes, making it HP.

 

[midlifeflyer]

I thought the turbo arrow used the same engines as the seneca and was rated to 215hp for something like 5 minutes, making it HP.

If there is some increase for the after-market turbo STC, it's not something I've seen.

 

[EdFred]

View attachment 91555
If there is some increase for the after-market turbo STC, it's not something I've seen.

Hmmmmm.... didn't they use the same engine on the Seneca and gave that a 215 horsepower rating? Maybe it's somewhat like the 540 and 2 different horsepower ratings between the Cherokee 235 and Comanche 250

 

[midlifeflyer]

Hmmmmm.... didn't they use the same engine on the Seneca and gave that a 215 horsepower rating? Maybe it's somewhat like the 540 and 2 different horsepower ratings between the Cherokee 235 and Comanche 250

Dunno. But I have definitely seen different rated HP with the same engine in different airplanes. If I recall correctly, the 172R at 160 and the 172S at 180 are the same engine, with the R de rated.

 

[JScarry]

One thing I’ve never got a satisfactory answer to is whether it is still possible to overboost with the Merlyn wastegate. With the fixed waste gate, it definitely is possible to overboost on takeoff, but since the Merlyn adjusts the MP automatically, I would think that it wouldn‘t allow overboosting. Nevertheless, I never let the overboost light come on.

After a while you can tell how much power to add on takeoff by the sound of the engine. I usually pull back the power to somewhere in the 33" MP, 2450 RPM, and 104+ kts range at pattern altitude.

 

[Jim Carpenter]

It's been a few years since I've flown a Merlyn equipped Piper, but IIRC, it is still possible to overboost with a Merlyn waste gate system. On takeoff, or anytime applying power, in general, you cannot simply firewall the throttle(s), it's necessary to gently advance the power levers while watching MP, stopping at the desired inches (whatever that limit may be) before reaching an overboost level. After awhile, your elbow/arm becomes "calibrated" so that you feel, just by repetitive muscle memory, how far to go for full power, with just a simple glance at the MP gauge to confirm setting.
As to power reduction and descent planning, I have always held to the one-inch-per-minute rule of thumb, providing for a gradual spool down of the turbo. Overly conservative, perhaps, and, I certainly don't need to use a timer, but, the point is, as midflifeflyer mentioned, you want to "coddle" that engine and approach any power changes with a smooth gentle touch.

 

[Archer Jack]

It has been many years since I sold my 77 PA28r-201T. It flies very similar to the Archer, so you should not have any difficulty flying it. It is nice to have the automatic gear extension backing you up. Maybe I was paranoid about shock cooling the engine, but power management (especially on decent) was always on top of the list. Long, shallow, high airspeed decents were my preference so I could avoid longer periods of low manifold pressure.

One other thing is to really look hard for any debris or nests in the engine compartment before every flight. I had FOD sucked into the turbo when I applied alternate air. It caused a rapid reduction in manifold pressure that fouled the plugs in flight.

May all your descents be decent.

 

[hindsight2020]

The only STC mod available is the change of the engine fuel plumbing to make it a TSIO-360-KB variant, which allows for the RPM to be redlined at 2800 and gives 220HP for 5 minutes, then it has to be reduced to a redline of 2600RPM for continuous. It's still considered a 200HP rating. This STC was generally combined with the installation of the intercooler (Turboplus), which is the vendor that provides both.