How do you sync a 4 propellor airplane?

[DrewBlows]

How in the heck do you sync a 4 propellor airplane? It seems to me that you would constantly be figiting with the prop controls to get rid of the "wah wah wah" sound. Is there some way to tell which engine isn't synced? Do all 4 engine propellor (and jet too I suppose) planes have syncrophasers? Help! This is one of those things that they should teach you in private ground school. Absolutly vital information.

 

[avbug]

No, not all four engine airplanes have syncrophasers or syncronizers. Those are handy, but for sissies.

You sync a four engine airplane exactly the same way you do a two engine airplane; one at a time.

 

[urflyingme?!]

Real men do it by ear.

 

[DrewBlows]

No, not all four engine airplanes have syncrophasers or syncronizers. Those are handy, but for sissies.

You sync a four engine airplane exactly the same way you do a two engine airplane; one at a time.

The reason that I thought it might be rather difficult to sync a four engine plane is that you would have a hard time differetiating the pitch of one engine from the other three. Apparently, you are saying that it is possible to tell if say, the engines on the left are synced, but one (or both) on the right aren't?

 

[EMB170Pilot]

blah blah blah


dont you have anything better to do on reserve

Where is your PS2?

 

[Cardinal]

How in the heck do you sync a 4 propellor airplane?

Very Carefully.

 

[bafanguy]

You sync a four engine airplane exactly the same way you do a two engine airplane; one at a time.

Well, actually, that's not the whole story. Mar and Asquared will jump in to refresh my memory. The DC6 had a prop master lever that controlled all props together and had a way to individually sync the props ( I see four toggle switches ? ). Can't recall the details, but don't remember prop sync ever being much of an issue.

As for the jets, the DC9 was synced by ear. The MD80 has the eng sync selector using N1 or N2. Works great.

The 727 ? Who knows ? Couldn't hear anything in the front; never heard any complaints from the back. But, out of sync N1 would beat the pax to death.

 

[Hugh Jorgan]

You pour a cup of coffee, set it on the aileron trim wheel in front of you and trim out the waves.

 

[DrewBlows]

blah blah blah


dont you have anything better to do on reserve

No. Well I have to go. I just got called in to taxi an airplane to the maintenance hangar. Seriously.

 

[414Flyer]

Yeah, its 3 time as much work to sync 4 props as opposed to 2. In the 4, it was all by ear, at least in the one I was in. Lets just say when going to a fire 10 minutes away, I was all a$$holes and elbows, and constantly bent over sidesways, moving the 4 mixtures, 4 cowl flaps, 4 props, 4 throttles, for takeoff, climb power, cruise, on the fire, coming back, descent, etc....Made for quite a busy new copilot

 

[pilotyip]

You sync 1 & 2 for phase sync and RPM, then you sync 3 & 4 for phase sync and RPM, then you designate #3 as the master and slave #2 to #3. Then you all four engines at the smae RPM and you do not have prop blades passing the front of the wing at the same time. Actually piltos don't do that, you tell the FE to sync the engines.

 

[DrewBlows]

Thanks for the replys. I just got back from the airport, I got to the airplane to find two mechanics (who would be taxiing the airplane), and one very pissed off captain who also had been called in from reserve. Oh well, (sh)it happens.

 

[avbug]

Well, actually, that's not the whole story.

Actually, that is the whole story. I don't know about this nighmarish difficult process folks are talking about, but syncing the props is not that big a deal. Especially if you've been in that aircraft and know how much to apply to each switch or lever. In the 4Y we did it with one hand, usually while doing something else. Either by ear, or using a set of standard gauges. No syncrophaser, but the gauges were there, and you merely set one prop at a time. Setting them by ear was just as quick, however.

In the C-130, for the really creative, the sync control box was on the right side of the cockpit, and could be adjusted manually with a screwdriver. A skilled user could move the center of vibration just about anywhere on the flight deck desired, and an old trick was to put the vibration under the navigator seat or under a crewmember's seat...after a flight, everybody felt good except that one person, who was irritable and didn't know why.

In the P-2, we shut two down after takeoff, and it wasn't really what was considered a four engine airplane, but a two engine airplane (R3350) with two jets.

 

[TurboS7]

One at a time.

 

[Spooky 1]

Syncro phase

More yet! Both the 1649 Constellation and the Lockheed Electra had "sycncro-phase" for smoothing out the props. This actually sensed the actual blade position of each propreller and put it into phase alignment with the prop next to it. The DC6/7 had a Master prop, either 2 or 3 and the propellers we synced by pushing a little buttion next to the throttles that would move each engines RPM by as much as 4% if my memeory serves me in an attempt to sync the props.

Having said that, I can recall standing in the head on an Electra, which was directly in line with the props and the vibration on the floor was great enought that you could lean left to right and sort of do a moon walk since the vibrations were so great.

 

[bafanguy]

The DC6/7 had a Master prop, either 2 or 3 and the propellers we synced by pushing a little buttion next to the throttles that would move each engines RPM by as much as 4% if my memeory serves me in an attempt to sync the props.

Spooky, That's what I was trying to remember. Props can obviously be synced by ear, but the systems devoted to the process can be elaborate.

 

[Spooky 1]

Spooky, That's what I was trying to remember. Props can obviously be synced by ear, but the systems devoted to the process can be elaborate.

Yea, think back to those golden years when you were an S/O on the mighty DC7. The Capt. would call for climb power and you, the ever so obiedient S/O would pull back the throttles to set the BMEP/MAP, then pull back on the Master Prop Lever, while at the same time pushing that little sync button so as to continually sync the props.

 

[mar]

The Magic Box

Ah, every single one of you guys forgot to mention the Magic Box.

I suppose the Synch Box could be a magic box (lower case 'm') but they usually didn't work very well when I sat in the middle seat.

The Magic Box I'm talking about is the Engine Analyzer used mainly for looking at the firing pattern on the spark plugs but it could also be used to synch the props.

As Spooky mentioned, usually you select either engine #2 or #3 as the master (watch the pattern on the Magic Box) and then decide if the others are either fast or slow and then adjust them from there--cussing the whole time.

I was just not very good at it. I think I had too much time in SC7 by the time I was an FE on the DC6. I was pretty much immune to the wah wah thanks to Garretts with really loose props.

 

[bafanguy]

mar,


Ya, still got my Engine Analyzer Handbook from Airlift Int'l ( crice 1967 ). Cariologists read EKG's, FEs read the analyzer. Can't claim to have ever understood it very well...double shorted secondary is bad, right ?

 

[mar]

Myocardial infarctions and blown jugs

Does the title of this post bother anyone else besides me?

Well, I suppose a double shorted secondary could be considered pretty bad since that jug would be cold.

And there's nothing worse than cold jugs.