can propeller reindexing check be carried out in flight?

[edwardlcy]

As per topic, can propeller reindexing check be carried out in flight? Any special consideration?

[Lkuest]

As per topic, can propeller reindexing check be carried out in flight? Any special consideration?

It's actually preferred to do it in flight. This allows for more stable conditions during the procedure. Refer to the 1C-130H-1, pg 1B-20. The only real consideration is during stable flight conditions.

[Steve1300]

It's actually preferred to do it in flight. This allows for more stable conditions during the procedure. Refer to the 1C-130H-1, pg 1B-20. The only real consideration is during stable flight conditions.

One would think so, but when the solid state synchrophaser were installed, safety-wire holes appeared in the resynch switches so that we could prevent the crews from doing it in flight. We are still told to safety-wire them on civilian Herks. Does the military no longer do that?

[Lkuest]

We still safetywire it with .20 copper. The procedure to resync in flight still in our -1 though. I think if we really didn't want the crews to do it, we'd safety it with .32 or .41. We might safety it with copper so that we don't accidently hit the resync switch during ground maintenance (even though the resync switch isn't powered until a master is selected). There's even a caution in our 61JG to not hit the resync switch while the propellers are static. If we do accidently hit it, it'll be pretty easy to identify that it's been accidently hit based on broken safetywire.

Without something written about why we do something, all you can do is guess, and that's my best guess. Anybody out there have a better guess, or some documentation as to why we safety the resync switch?

[tenten]

Yes, Lkuest; Ref. Maintenance manual (SMP 581) chapter 61 Quoting:

CAUTION:

When the propellers are static, do not use the prop resynchrophase switch. The static propellers do not furnish any pulses to the system, so with electrical power supplied and the master selector switch turned on, operation of the prop resynchrophase switch drives the speed bias servo in each slave propeller to its plus 2 percent limit, due to inherent characteristics of the synchrophaser, each actuation of the switch allows an additional 2 percent change in governor setting, and after three actuations the slave propellers would be set at their maximum value of 106 percent.

The electronic system would then be essentially on neutral in regard to the feed-back potentiometer position. Selection of the other master engine by the selector switch could then result in the first master also being driven to the extreme maximum position. In mechanical governing 100 percent rpm would be obtained, but placing of the sync-servo switches in "normal" would cause the slave engines to return to their previous setting of 106 percent.

Therefore;

Another Quoting: Ref. TO 1C-130H-2-61JG-20-1

NOTE:

If there is none, a hole must be drilled in PROP RESYNCHROPHASE switch to accommodate safety wire in following step....... etc.

Seems they insist in locking that switch to avoid the 106%.

[bobdaley]

Which brings up the question? What about the J model? Do they select a master engine, sync, resync, reindex etc? Is all that kind of stuff automatic?

How would a 1000 hour AC and a 300 hour CP do all that without an FE?

Bob

[Lkuest]

The J is very similar in that you select a master propeller, and you may select either 2 or 3. From there, things change. The propellers on the J generate six pulses per revolution in stead of 1. FADEC A synchrophases all slaves to within 1% and 2 degrees of phase angle. On the 54H60 prop, resynching is done to establish a relationship between the electronic and mechanical parts of the valvehousing via a clutch and brake mechanism so that the electronic synchrophaser always knows what it's telling the hydromechanical pilot valve to do (calibrating the feedback pot to the pilot valve). On the J, the pitch is controlled 100% electonically via the the FADEC to maintain 100% rpm as measured at the power turbine. In synchrophasing mode, the FADEC varies RPM slightly to establish a proper phase angle, then readjusts to 100% rpm to maintain that same phase angle relationship.

The FADEC tells the hydraulic Pitch Control Unit what to do, and the PCU reports back what it is doing via Transducers. There are no clutches to slip, and the dowty is so precise that no resynching is required to establish a proper relationship. The 6 pulses per revolution produced by the propeller synchrophasing system may also be used to measure RPM if needed.

I'd be curious to know how the NP2000 does it.

[super71]

The NP2000 does away with the syncrophaser.

[larry myers]

Which brings up the question? What about the J model? Do they select a master engine, sync, resync, reindex etc? Is all that kind of stuff automatic?

How would a 1000 hour AC and a 300 hour CP do all that without an FE?

Bob

Bob,

It's probably all automatic so you guys can't screw it up. In addition, just think, your also in charge of flt. deck air temp.