14 March 2006

Aviation Surprises

In order for an aircraft to fly in the U.S., it must at least be inspected annually to insure it is "airworthy". Aircraft flown commercially undergo a much more rigorous inspection process.

Obviously this is a good thing for many reasons. It not only keeps aircraft from falling out of the sky at alarming rates......the system fosters confidence in the flying fleet within the aviation community, and more importantly, in the civilian community as well.

If a problem is found in a certain make and model of aircraft, the FAA considers whether this problem is an isolated incident, or if there is a likelihood it is a problem that will crop up in more of this same type aircraft.

The R22 I use to train students has a rotor blade made of aluminum (Aviatrix....that's aluminium), and stainless steel. In very damp climates, particularly those close to salt water, many R22's have been found to have what is called "dissimilar metal" corrosion. Different metals, when damp, begin to act as a battery, and the electrolysis process eats into the joint where they meet, weakening it. The FAA rightfully issued a service bulletin for the problem.
The Robinson factory agreed to replace the rotors on those machines still under warranty, and will pro-rate the replacement of all rotors, depending on their total time.

The trainer I use is hangared continually and is not subject to a great deal of moisture.
Still, I'm glad to put on new rotor blades, because the aircraft could be sold to a new owner that lives in say, Miami, Florida, where the problem could be serious. This helicopter is new enough that the blades will be replaced free of charge. Replacement will take about 3 weeks.

We started the process last week by cutting off the rotor blades. We measured two feet out from the main rotor hub and took a saws-all to these $10,000 rotor blades. We then sent the rotor cuff and blade root to the factory where they will inspect the blade spindle for damage, and finding it undamaged, will fit the new rotor to our old spindles.

Taking a saw to what appears to be a perfectly good rotor blade is an emotional experience.
Add to that the fact that it grounds the trainer for at least 3 weeks, and you begin to see the economic impact that is caused in this little segment of the aviation industry.
Think of the impact of a major change to a large number of aircraft........rudder improvements to the Boeing 737, for instance, and you can see why aviation will always be an expensive, risky business in which to make a living.

I've got four students sitting on their hands, wondering how much proficiency they will lose while this aircraft is grounded.
But we'll all be more comfortable knowing the rotor over our head is likely to remain in one piece, thanks to a diligent inspection process.



Sitting around on their hands?? Time for a block of instruction on navigation.

Greybeard said...

Wish that would work, Dave.
But all the ground schooling in the world is not gonna keep your skills sharp on an aircraft as difficult to fly as a helicopter.

Under the best of circumstances there is regression if the student doesn't fly regularly.
Three weeks away from the controls will require some retraining.

Isaac Niedrauer said...

Nice site you have here! Helis are interesting that's for sure!