prop ground clearance on twins?

[alaskan9974]

Curious what prop clearance is like on twins, specifically twin comanches, baron 55/58's with three blades and senecas? Comparable to their single engine counterparts or lower?

 

[Larry Vrooman]

14 CFR § 25.925 requires at least 7 inches for nose wheel equipped aircraft, regardless of the number of engines.

Beyond that, one of the reasons that people go with three bladed props is to increase clearance and reduce tip erosion. Consequently comparisons between say an individual Bonanza and an individual Baron, or a specific Arrow and a specific Seneca will often come down to the propellers actually installed.

Not having a tape measure along over the years and not measuring I can't say that I recall any significant difference in general.

 

[Bell206]

Comparable to their single engine counterparts or lower?

In what context? There's a lot of variables to the answer. For example, the 7 inch certification minimum mentioned above can be conditional regardless if the aircraft was certified CAR 3, Part 23, or Part 25.

 

[Ted]

It’s highly variable. The Aztec’s props are pretty low to the ground. Twin Cessnas stand tall. Etc etc. like anything there’s the minimum cert requirement and what’s done.

 

[TigerGene]

Take a corner too fast in a 285 hp Baron with 2 bladed props and a strut just a little low and you may find the very tips of your props have a flat end. Seen plenty of them in my “night freight days”.

 

[denverpilot]

Think you got answers but to combine them...

Seven inches, but not all really are, and it’s easy to get stupid and lower in ground handling if you forget you’re taxiing something heavy with a lot of weight out there in the wings (engines and fuel) that’ll help you screw up when you corner too fast.

Not to mention the gear on some really doesn’t like that.

The good news is, you’ll likely be on hard surfaces almost all the time. If not, more blades may help as someone also mentioned.

If you’re not flinging the thing around, your risk of a prop strike is way higher from forgetting the gear handle, rather than prop clearance, according to NTSB reports.

It’s worth reviewing those for any type you might be interested in flying, let alone buying — some have specific accident patterns that can be better avoided if you count the causes up. Or type specific oddities.

People like to turn engine out emergencies into low drag-it-in and get too slow and crash a couple miles short of the runway events in a couple training types I flew. Started with many thousands of feet of altitude AGL and plenty close to an airport, and still didn’t plan well enough to make the runway.

Makes no sense but it’s right there in the accident reports. Super odd.

 

[schmookeeg]

Curious what prop clearance is like on twins, specifically twin comanches, baron 55/58's with three blades and senecas? Comparable to their single engine counterparts or lower?

Same gear legs between my 35 and 55.

My IO-520 2-blade prop in the Bonanza was 82" diameter. When I put an IO-550 in it, it required a move to a 3-blade, 78" diameter.

I've not had a 2-blade Baron, but both of my 3-blade Barons (IO-520E and IO-550C) are also 78".

So they're the same props. I'd need to measure the baron nacelle placement relative to the nose firewall on a bonanza. I suspect the Baron clearance is an inch or two shorter. The dihedral on the wing doesn't really get that high where the nacelles are placed.

My next-door hangar neighbor has a P35 and I have his door code. If you're looking for science I can go measure them both in whatever detail you'd like.

 

[JTA]

Any of you ever take a Baron or Seneca to AirVenture? I’ve been plenty of times in singles but hesitate in a twin. Thinking about bringing a Baron or Seneca in 2021 but the “pull off into the grass” bit makes me nervous. Especially the potential drop from asphalt to grass.

 

[Kristin]

Prop clearance on a Twin Comanche is no problem, unless you are going for seriously uneven or potholes runways, in which case there are few tricycle gear twins that really should be on the strip.

 

[schmookeeg]

Any of you ever take a Baron or Seneca to AirVenture? I’ve been plenty of times in singles but hesitate in a twin. Thinking about bringing a Baron or Seneca in 2021 but the “pull off into the grass” bit makes me nervous. Especially the potential drop from asphalt to grass.

Not personally (yet), but if I did, I would bring 3 plywood squares to place under the gear so they don't sink into the grass. Particularly if it has been raining.

 

[Doc Holliday]

14 CFR § 25.925 requires at least 7 inches for nose wheel equipped aircraft, regardless of the number of engines.

Beyond that, one of the reasons that people go with three bladed props is to increase clearance and reduce tip erosion. Consequently comparisons between say an individual Bonanza and an individual Baron, or a specific Arrow and a specific Seneca will often come down to the propellers actually installed.

Not having a tape measure along over the years and not measuring I can't say that I recall any significant difference in general.

Part 25 is for Transport Category Airplanes. I doubt seriously it applies to this conversation.

 

[Waltthepilot]

I wouldn't recommend taking a heavy aircraft like a Seneca to Oshkosh unless you are willing to pay the hard surface tie down fee. A friend of mine had a prop strike there on his twin Navion when he was marshalled over a pothole. Visibility taxiing in our Seneca isn't the best when trying to do close quarter maneuvers with gophers.