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ROTORwrench…Tips, Tricks, and Info - April 2016

Posted 8 years 37 days ago ago by Scott Skola

Helicopter Maintenance Blog
April 2016

Looks like the old B model…well, not exactly old…nor a true B…but at least it has a 206 M/R on it…any hoots…the Bell 505 looks to close in on 400 total orders this year. I guess you can say it’s pretty in its own way.  I wish them luck.

Truth be told, when they stopped production on the Bell 206B, I did shed a tear or two. I had cut my rotorwing teeth on a B model. The good old days of cable operated rotorbrakes, and pan floats you could pack in your sleep. But, then again I also liked the SA315B, BO-105 and triple deuce.

Moving along….

ATA 71

Multiple Models
Received a couple replies related to last month’s tip. Some common problems associated with bleed air systems are: bleed air supply valves that stick under pressure, corroded electrical connections, excessive system leakage, and faulty temperature sensors.

On valves that stick, one primary cause is compressor wash soap remaining in valve after complying with engine wash. Where possible/convenient disconnect air system line upstream of valve prior to wash. If unable, use a second rinse bottle per engine to flush as much soap as possible. Be sure to turn on bleed air system during engine drying run for a full two minutes or as recommended by manufacturer.

Another culprit on sticky valves is the water quality used during the engine rinse/wash. Deposits build up on valve internal parts causing intermittent operation. Most maintenance manuals define water quality requirements, but for a quick check fill a glass jar with a small amount of water. Leave in sun to evaporate and see what’s left.

Corroded electrical connections can be prevented with Dow Corning 4 or Stabilant 22 applied to the contact pins, and a light coat of an LPS product, or equivalent, to the exterior of the connector.

Excessive leaks and faulty sensors are normally a remove/replace option only. One way to verify system leaks is use a commercial Leak Check product or dish soap/water blend that will indicate bubbles at suspected air leak.  If accessible, for temperature sensor checks, you can use a heat gun/thermometer on the temperature sensor to see if it operates at the required setting. [Submitted by BigD and JW]

Thought we’d finish getting up to date on FAA Special Airworthiness Information Bulletins (SAIB) issued since latter part of 2014.

First one is on multiple model rotor drive flange nut inspections.

This one is on multiple model air conditioning system wiring.

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.  He can be contacted at [email protected]

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