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ROTORwrench…Tips, Tricks, and Info - July 2017

Posted 6 years 317 days ago ago by Scott Skola

ROTORwrench…Tips, Tricks, and Info

Helicopter Maintenance Blog* 
July 2017

Looks like we got a couple “new” aircraft types entering the market place within the next year or so. The first production Bell 505 landed at a Bell Training Center recently, where they will begin training instructors and eventually the initial pilots and mechanics.

On track to receive its FAA certification in 2018, the AW609 civilian tiltrotor is destined to make a splash. While neither of these aircraft are considered brand new technology, it will be interesting how they will integrate with the legacy aircraft. 

Considering all the hoopla over these “new” models, I wonder how popular they will really become. I guess only time will tell. 

Just a reminder I’m still off the grid. Be back in August.

And now more from the Lama-Nator…

Airbus (Sud Aviation)
SA315B Lama

Again, continuing with a Lama daily inspection and associated tips and tricks. Sump the fuel 1st thing.

The Main Driveshaft and Freewheel is a peculiar item on the Lama. An easy way to tell if someone is a Lama mechanic is to ask them if they know how to R & R the freewheel, because there are two peculiarities about it that befuddle folks until they’ve seen how it’s done. 

Without installing the gaskets, place the shaft with the freewheel mechanism close to the Main Gear Box. It does not fit directly square into the space. You must put one corner of one end in first and while collapsing the bellows seal flanges, angle the opposite corner of the other end in and squirrel, or roll, the shaft into place. Great, that’s half the battle. Now, the paper gaskets, you put them in after. 

Stiffen them up with Fuel Lube and slide them in one at a time by collapsing the bellows seal flange and working the gasket down into place. Do the same for the other end gasket, forcing the shaft toward the end with the gasket already installed in order put in the other one. Line up the holes with a punch.

You’ll likely not figure all that out without some guidance, so you can misrepresent your Lama experience to get a job, but you may be humbled if you’ve never changed a freewheel. And that’s not all to the freewheel shaft install--you have to wrap each of the 12 attach bolts with 3 turns of Teflon pipe tape. 

Now, down under the helicopter we’re checking the lower mixing unit closely for cracks and loose bearings. While we’re here we’ll grease the crank arm or Disc Rod, the only zerk on the mixing unit. It’s a daily item.  Apply grease until it purges out all the gritty grease from between the disc and the side plates.

Let’s go ahead and pull the belly panel and have a look at the T/R pedal assembly. The aluminum pedal levers have plain bronze bearings that swing on a steel shaft. There is no periodic maintenance prescribed for this assembly and these bearings. In time, the grease that may have once coated the shaft, dries up and it then seizes to one pedal lever bearing and then the other. 

Disconnect the T/R control tube to the T/R quadrant. This isolates the T/R hard linkage from the cable part of the system. If your tail rotor pedals are stiff, you need to investigate the assembly and establish your own periodic lubrication of the shaft and bearings. One operator applied a Zerk to the pedals.

Another thing about the T/R pedal assembly is that the shaft is held between side plates by external circlips in a groove on each end. These circlips have been known to pop off the shaft, especially if they have been removed several times and have not been replaced with new. When this happens, one pedal sinks into the floor, rendering a dangerous situation. A modification called a T/R pedal failsafe, a long bolt inside the pivot shaft and large washers each end gives secondary security to the assembly.  

Back up top, look at the Main Gear Box oil in the sight. If it’s dark or cloudy you may have a problem. Dark oil is sometimes due to the degradation of the internal varnish coating of the gear case and is the subject of a Service Bulletin. Cloudy or foamy oil means there is water in the gearbox oil. Much damage due to internal corrosion has been attributed to this, especially if the aircraft sits for periods of non-use.
[Submitted by Lama-Nator]

The 2016 Spring and Summer AgustaWestland newsletters:



SUBMITTING MAINTENANCE TIPS/TRICKS/QUESTIONS/INFO: Have an old tip or trick you’d like to share with your fellow mechanics? Or maybe a question that you can’t seem to find an answer to? Or just some info to pass on?  Send an email to: [email protected]

About the author: After 32 years maintaining helicopters in various capacities, Scott concluded a full time career with a major operator in 2014. When not pursuing future writing projects, he can still be seen around the flight line tinkering on aircraft for beer money. 

*To keep the hounds at bay, the information contained in this blog is for discussion purposes only.