Posted 92 days ago ago by ScottSkola 1 Comments
Helicopter Maintenance Blog*
As the maintenance end of the industry continues its shift to a new safety culture, more articles are being written on the topic. I ran across two articles from 2016 that give a different viewpoint on where maintenance operations are going.
For those who wish to read, they can be found on page 24 and page 27 here:
Well, I’m off to the Land of the Midnight Sun for 2 months. You can still send your emails, but there will be a bit of a delay in my reply. Back in August.
Till then the Lama-Nator has graciously stepped in with a few Lama/Alouette tips this month and next.
And a way we go….
TIPS and TRICKS:
Airbus (Sud Aviation)
SA316 Alouette III
Remember the Lama tip from March 2017 I introduced the Alouette III, the sister of the Lama, and the master aircraft on Type Certificate H1IN, of which the Lama is a version? The Lama has the same drive train components as the Alouette III with the exception that the tail rotor drive shaft is several inches longer on the Lama. That’s what gives the Lama its phenomenal tail rotor authority, the extra-long tailboom.
The controls and instrumentation are also same/similar, but the likeness ends there. With its large cabin and skinned tailboom, the Alouette III flies like a billboard. By contrast, the Lama is immune to wind (up to a certain point) because it has a small cabin and an open tailboom. A number of high-time Lama pilots, as well as inexperienced Alouette III pilots, have perished in Alouette IIIs due to thinking they were flying a Lama, misunderstanding or underestimating its behavior in gusty winds.
In addition to quite different flight characteristics than the Lama, the Alouette III has wheeled landing gear with hand-pump locking brakes on the main wheels. These brakes are not treated with the respect they deserve and they have been responsible for numerous incidents and accidents over the years.
Consider this event: Alouette III landed, began to roll forward on slightly sloping helipad. Adding to the drama, there is a rocky sloping drop-off beyond the pad and the pilot has already chopped the throttle when he notices the slow roll. As he slams the throttle back up, over-temping the motor, he pulls pitch and aft cyclic, causing the main blades to contact the tailboom. This Alouette III had such notoriously bad brakes that a set of chocks were carried under the back seat!
Of course the system is susceptible to leaks at the wheel cylinder and plumbing. Despite the manufacturer’s instructions which include elaborate special tools, the system can be bled like a car’s brakes through a bleed screw located at the wheel cylinder.
Pump up the brakes, release the air at the bleed screw, top off master cylinder, repeat until the fluid level stays up. A veterinarian’s hypodermic is best for refilling the cylinder as it has a small port. Tap the brake block (master cylinder) to release air bubbles clinging to the inside. You may find that the brake block is bad, won’t hold, and needs replacement.
The tip is this: when confronted with an Alouette III, in conjunction with the pilot, a mechanic should bleed the brakes and monitor them for a day to see how well they hold. It is likely that the brake system just needs bleeding, and you would be advised to draw the line at one full day for their ability to hold. Less than that and you run the risk of having them release when you most need them during a day of flight operations, like in the example above.
One myth about the brakes is that they involve a nitrogen charge to the master cylinder, which is true, but the nitrogen charge only pops the red button up when the brakes are released or bleed down.
Moral to the story: DO NOT FLY ALOUETTE III WITH BAD BRAKES!..... BRAKES ARE REQUIRED for LANDING, WHICH IS PART, the LAST PART, OF FLIGHT…. GROUND THAT HELICOPTER!
A couple 2017 Robbie 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@example.com
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.
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