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Helilog

R44 Vibration

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My R44 was smooth as glass last week, now it shakes bad, I left it out side and put the blade booty covers on. it snowed and it melted and the water filled the blade end and booty full of water, then it turned to ice. I had a hard time removing the boots, had to use a heat gun on them to melt the ice, then removed the end caps on the blades, one was full of ice. Vibration was so bad at first i had to shut it down before removing end caps. The blade doesn't look dameged or delamanated, put a strait edge on them and they look good. Any body have any idea's or suggestions.

 

Helilog

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My R44 was smooth as glass last week, now it shakes bad, I left it out side and put the blade booty covers on. it snowed and it melted and the water filled the blade end and booty full of water, then it turned to ice. I had a hard time removing the boots, had to use a heat gun on them to melt the ice, then removed the end caps on the blades, one was full of ice. Vibration was so bad at first i had to shut it down before removing end caps. The blade doesn't look dameged or delamanated, put a strait edge on them and they look good. Any body have any idea's or suggestions.

 

Helilog

You need to get your AME to inspect and service the blade boots. They are supposed to be filled with hydraulic fluid and be air free (IE bled of air).

 

Also, as far as ice in the blade tips, there have been a few R44 Safety notices and service bulletins from Robinson on bond line separations at the tips of the blades. They are good reading and I highly recommend them.

 

Unless you are qualified AME don't mess with this stuff. Get a pro to have a look.

 

Good luck.

 

RTR

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By blade boots I ment to imply the "red tie downs for the blades" not the rubber boots on the grip end of the blades, Thanks, I hope I just have to send them out for balancing, and not to buy another set of blades. I know Robinson has a new style out with a stainless steel covering to make them tougher, but still $43,000.

 

Helilog

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By blade boots I ment to imply the "red tie downs for the blades" not the rubber boots on the grip end of the blades, Thanks, I hope I just have to send them out for balancing, and not to buy another set of blades. I know Robinson has a new style out with a stainless steel covering to make them tougher, but still $43,000.

 

Helilog

 

Have a pro inspect the blades. Was there more ice in one tip than the other? Approx how much ice accumulated in the covers? Note that excess weight at the tip can damage the spindles. Also steel skinned blades dent a lot easier. A straight edge will likely not tell you what you need to know. Check out the link below. Cheers

 

http://www.ainonline.com/ain-and-ainalerts/aviation-international-news/single-publication-story/browse/0/article/robinsons-switch-to-steel-blades-gets-mixed-reviews-17235/?no_cache=1&tx_ttnews[story_pointer]=1&tx_ttnews[mode]=1

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Only one blade had ice, the other was higher up at the tail boom, so the water ran out. The end cap was full when I took it off and a 2 in square chunk was in side where the weigh screws are.

 

Helilog

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Only one blade had ice, the other was higher up at the tail boom, so the water ran out. The end cap was full when I took it off and a 2 in square chunk was in side where the weigh screws are.

 

Helilog

Blade Debonding

In Service Bulletins 61 and 96, issued last year, Robinson noted that main rotor blade skins can begin to debond (separate) at the skin-to-spar bond line on the lower surface near the blade tip. Debonding can occur when the bond line is exposed due to excessive erosion of the blade finish, or when corrosion attacks the internal tip cap. Robinson recommended that operators use visual inspection and “tap tests” (tapping the bonded areas on a blade with a coin) to detect delamination.

 

 

The FAA followed the Robinson Service Bulletins with an Airworthiness Directive in January. But the NTSB wants even more elaborate bond-testing methods. Citing two 2006 in-flight break-ups of R44s due to fractured blades, in June the Safety Board recommended the adoption of long-term durability testing of adhesive bond joints for helicopter main rotor blades and the requirement for Robinson to “develop a nondestructive inspection technique or combination of techniques capable of consistently detecting bonding defects, such as voids, debonds and weak (kissing) bonds, in bond areas between the skin and spar at the tip of the blade and between the skin and tip cap for R22 and R44 helicopters.”

 

 

 

After reading the above article which took about 7 seconds to find with google am guessing you have debonded your blade with the heat gun. Heat and glue generally don't go together. After you replace the blade use de-icing fluid or gentle heat in future.

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After reading the above article which took about 7 seconds to find with google am guessing you have debonded your blade with the heat gun. Heat and glue generally don't go together. After you replace the blade use de-icing fluid or gentle heat in future.

 

If there was still ice in the tip weight pocket after heating the blade to get the "booty" off, I dont think debonding is the problem, although you are dead right about heat and glue (reason the blades are painted white on upper surface to reflect sun heat). It takes about 80 degrees C to degrade the bond.

 

There may still be ice behind the mass balance weight in the spar (very difficult to see) that has not been removed.

 

I am assuming the vibreation is lateral???

 

Nutmix

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Balanced an M/R R44II, 285 TTSN. Got vertical and lateral 0.06 ips but the aircraft has a 2 per rev above 100 knots (about 0.8 ips).

 

Ran out of time, did not have time to check teetering hinge friction. It’s quite a drive to get back to the aircraft and would like to have a couple of ideas before I return to the aircraft.

 

Has anyone had any luck eliminating/reducing a 2 per rev on an R44?

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Are there any worn rod ends on pitch links or control tubes? Swashplate shimming loose? Flapping hinge friction?

I assume 2per is vertical?

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The rotor head (Swashplate included) is the best I have seen, which is not surprising considering its only got 300 TTSN. Flapping hinge friction is less than teetering, and teetering friction seem to be on the high side. I detected the vibration on both the lateral and vertical sensors. Was about a 1 ips when the 1 per rev vertical was at 0.35. Then came down to 0.8 ips once the vertical 1 per was corrected to 0.06.

 

At or below 100 knots the 2 per is around 0.5 ips and the aircraft feels really good, but once the speed in increased above 100 knots the vibration become “present”. I advised the customer to simply fly at 100 knots (what’s 10 knots going to gain you), but he found this unsatisfactory, and countered with the valid point that “it didn’t do that before”. Help.

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