Wednesday, June 20, 2012

Lack of Mixture Travel

The right mixture lever has been stiff to move out of idle cut-off for weeks now. If I were writing in my old style of bombarding you with every trivial detail of my every day you would have heard it mentioned with every engine start. It seems to be better during the flight, and then worse again the next day. I complained about it to maintenance and they said there was nothing wrong with it. I complained about it to maintenance and they said they lubricated it.

It didn't really seem like the sort of issue that would be solved with lubrication, and it wasn't. Sure it was a lot better after they started, but so was it a lot better at the end of a flight. But at the beginning, wow. I wouldn't push an airplane part that hard for fear of breaking it, if you hadn't been led to do it, bit by bit, a little harder each day. My Person Responsible for Maintenance gets daily updates on this issue. (And every other issue. A contributing factor to my blogging hiatus was a PRM who actually appreciated daily reports that look kinda like an Aviatrix blog entry). One day it took three tried to start the right engine, not through any fault of the engine, but as I got a start I wasn't able to push the mixture lever far enough forward to sustain fuel flow before it died. It was STIFF. Third time lucky and we ran up and took off.

Barely off the runway and the right EGT needle flew right through the red bar into the territory beyond numbering, while the right engine fuel flow was about six gallons per hour lower than usual. I can see that split on both my analogue and digital fuel flow gauges. (Yeah, we use funky units like knots and gallons per hour: this is what my instruments read in. I guess I should be happy it's not furlongs and firkins per fortnight. You don't really have to know what a gallon is, just that less of them are going through the engine than usual). If gas is what's burning in the engines, why would less gas give more heat? Gas delivered to the cylinders in excess of the stoimetric necessity serves to cool them, so while not required for the chemical equation, those six millilitres more per second are definitely included in the manufacturer's equation for aircraft serviceability.

There are no obstacles ahead, so I lower the nose (which speeds us up and increases cooling) and start pulling power off the right engine until the temperature come down. It's a little below our normal cruise power. We've just come off a northern airport with no ATC and no one who would service our airplane. I call centre--or possibly they were calling me--to cancel the IFR, with no explanation, and turn south VFR. South to where people with parts and tools can make my airplane work right. South to where our cellphones work. Text messages fly. We have to choose between two likely airports. At one of them company hasn't been able to contact the purported maintenance outfit. At the other company has, but they have said they don't have the time to do it. Wherever we land, that's where we are until it's fixed, because it's not reasonable to do another takeoff if it's going to drive engine instruments through their limits like that.

We pick an airport and land. I finish the paperwork, including writing the snag in the logbook so I can't have an attack of stupidity and decide that it wasn't so bad after all. The other crew member goes to find someone to work on the airplane. He finds no one who can spare even the time to come and look at the problem. I say oh well, I'll just check that it's okay to park here, and wander into the nearest hangar doing the hello thing. Every time I do that I'm cognizant that I'm kind of trespassing, wandering around between someone else's expensive and secured aircraft, but usually the only way to find someone in a hangar is to wander in and follow the sound of the radio or the pneumatic tools until you see someone. I've never once had the reaction be fury or distrust. In this case the folks I find look and sound suspiciously like maintenance engineers.

"Hi, I came to ask you if it's okay to park outside against the fence, but you look like you could answer a more important question. Do you know anything about piston twins?"

The world of aviation maintenance is divided into camps based on the kind of engine (turbine vs. piston) and wing (fixed vs. rotary). This guy turns out to be qualified on just about everything, and has some time to spare. I bring him back to the plane. My co-worker (and boss) laments, "I go all over the airport looking for an engineer to look at our airplane and you find one in two minutes without trying?"

He pulls an engine cowling and pokes at the throttle quadrant a bit. We need the mixture cable replaced. I can't see what he sees, even with a flashlight, but I am unsurprised. He can't help us, though, because his contract forbids moonlighting. He's still been a help.


nec Timide said...

Indeed, sometimes identifying the problem is 90% of the solution.

Ben Read said...

"If I were writing in my old style of bombarding you with every trivial detail of my every day ..."

You say that as if it were a bad thing.

A Squared said...

@ Aviatrix

"If gas is what's burning in the engines, why would less gas give less heat?

Did you mean to write less gas, more heat? The problem was excessively high temp, right?

A Squared said...

"I go all over the airport looking for an engineer to look at our airplane and you find one in two minutes without trying?"

It was the sexy hose and the green hair that did it.

Scott Johnson said...

I was about to correct "stoimetric," thinking that you meant "stoichiometric," but Googling turned up several occurrences of your exact spelling. I can only assume it's an accepted shorthand.

Oh, and for the record, I liked the excruciating detail too. :)

capnaux said...

...I think most of us "aviation geeks" that read these blogs love details details details, but I think you've mastered the Art of the Balance between story and minutia!

I agree it's the "hose n hair" that got mx in record time, lol!

Seriously, though, good story. Flying Part 91 (as opposed to 121), you have both more options and more problems...can land anywhere and get anyone qualified to work on the problem...but then comes the challenge of finding someone!

Thanks ;)


Pete Templin said...

Maybe stand near your aircraft with a clipboard and tell everyone, "This aircraft is SECURED to go NOWHERE!"

Michael5000 said...

I'm not sure why "firkins per fortnight" was a killer laugh-out-loud-and-roll-on-the-couch-a-little line, but I think it means I'm a Cockpit Conversation reader.

JetAviator7 said...

I find all of this detail great reading as you can never learn to much as a pilot and there may come a time when you need all the information our brains can hold.

Keep up the great writing, grab your aviator sunglasses and keep flying!

Sarah said...

Sexy hose and green hair? The hair I've seen pictured, but the only hose I've heard described was orange or black scat. Hmmm. Maybe that does go with green hair.

A Squared said...

" . . . but the only hose I've heard described was orange or black scat."

There was some earlier discussion of Aviatrix' hosiery. It may have been before you started reading.

Crispy Kale said...

What does that mixture cable look like? Braided steel cable in plastic housing? I'm visualizing the throttle cable on a 4-cycle piston lawnmower, or the brake or shift cable on a bicycle. Thanks from Duluth, MN-almost to ON.

GPS_Direct said...

I love spam, if for nothing else than it focuses on the sheer stupidity of the masses. (Not any "masses" in here, are there??)

Who on earth would think that spam-bombing aviation blogs would lead to sales of their gyroplane?? Gyroplane?? The entire worldwide sales volume is probably something like 2 per month. But, hey, now that 'Trix has been spammed, I'm sure we'll all buy one to do some "crowd control and policing." Wait... "Crowd control?!?!?" In a gyrocopter??

Email spams are just as entertaining... The sad truth is that people spam us because it works. For every 42 million of us out there, there's some poor schmuck that figure he'll buy some "v1@gra" from some website with a malformed url... And you'd think there couldn't be anybody on the planet that hadn't heard of the rich, Nigerian General (does Nigeria even have Generals?) that only needs $150 dollars to give you 35 bazillion urkels or whatever. But the spam still comes... Lol.

(Interestingly, one of my spam check words is a photo... Seems they've bypassed that too.)

Aviatrix said...

Oh rats, I perma-deleted that spam right before seeing that you had commented on it. And it was pretty funny. Had the spammer left just one copy I might have left it, but he tried to put it on a number of posts.

Aviatrix said...

I left the crowd control gyroplane on the June 14th Wingnut post, just in case anyone wanted to have a look at what GPS Direct was commenting on.

Aviatrix said...

And A Squared was quite right regarding less/more heat. I fixed it.