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Aviation Safety

AVIATION SAFETY

Dave Fry, WVFC CFI and Aviation Safety Counselor dgfry@aol.com

 

When Things Go Wrong: Variations on a Theme 

A recurring theme in my newsletter articles has been that things occasionally go wrong in airplanes.  Sometimes, it’s pilot error; sometimes it’s controller error; sometimes it’s the plane.  And, of course, the more you fly, the more likely it is that you will have one (or more) of these things happen to you.

Here are two recent cases:

QUESTIONABLE BRAKES

I was returning to HWD from SoCal in a Pilatus one night recently, and after setting the brakes, did my normal preflight inspection, in which, as usual I found nothing wrong. As I got to the “Starter – PRESS” part of the checklist, I pressed the brakes (even at idle, an engine that can crank out 1500 HP is quite capable of moving an airplane) again.  The left pedal stayed pretty much where it was, but the right one went down a fraction of an inch.  Not enough to raise any eyebrows, but something to consider and “note to self” to see if it happens again.  Taxiing to the runway, everything seemed normal, and fortuitously, I didn’t have to stop at the end of the runway, but got cleared for my IFR departure prior to HWD reaching the end of the runway.

Following my landing back at Hayward, I noticed a bit more travel on the right brake than on the left, but by pumping them once, they were back in synch.  During the taxi to APP, the right brake still felt a little “soft” for lack of a better word, so I figured I’d report it.  Turns out it was a good thing.  The next day the mechanic looked at the brakes, and unscrewed the brake line with his fingers – no wrench required.  Somehow, I doubt this was the factory accepted torque setting.

I was probably a couple of stops (brake applications, not flights) away from having no brakes on the right side.

WHEN THE POWER MAKES NO SENSE

Taking off from Hayward recently in a Pilatus, I got a ding and a red light as I brought the power up.  Since the engine can over-torque on the takeoff roll, especially when the plane is cold, I reflexively reduced the power a smidge (an amount calibrated to remove the red light and continue the takeoff), and flew non-stop to San Carlos to pick up the owner and a couple of other passengers.  That flight is so quick, and so busy that if there was anything wrong I didn’t notice.  Well, obviously, if there had been anything sufficiently wrong that it would create an Amber Alert or a Red Warning, I would have noticed.  Aside from a ding that is painfully loud, it won’t shut off until it’s acknowledged,

An hour later, I had loaded up my passengers (the airplane’s owner and a couple more) and started taxiing for takeoff.  The plan was the San Carlos One departure, up the coast to Seattle, and dinner at Verrazano’s.  OK, so a couple of those aren’t actually on the flight plan.

During an enroute climb, power is set to either 36.9 PSI or 780 degrees ITT, whichever is reached first.  And in EVERY previous flight, 36.9 is reached before the temp comes up anywhere NEAR 720, to say nothing of 780 until the plane is above FL 200.  Yet on this flight, we were temp limited almost immediately after takeoff, and that isn’t normal, which caused me to wonder why.  Curiosity may kill the cat, but it can keep a pilot alive.  Trying everything I could think of (Inertial Separator closed, Bleed Air inhibit) I got no improvement, and, no surprise, there is nothing about this in either the POH, or in the emergency checklist – I checked.  As I continued to puzzle out what the crud was going on, I listened to the plane.  Everything except the power-temperature relationship seemed, sounded, and felt normal.

At 10,000 feet, instead of being able to get 36.9, we maxed out on the temp at just over 18 PSI.  Two thoughts occurred to me – first, maybe there was a bleed air leak, but I wondered why it didn’t show up as an engine fire (hot air in the engine compartment triggers a fire alarm).  Second, maybe it was a temperature sensor issue.  I wasn’t even TEMPTED to act on that one.  If the temp was real and I over temped it, the cost would be a smidge above $1,000, 000 and it would be an RGE (Resume Generating Event for the uninitiated).

At this point, I’m no longer going to Seattle, and need to break it to the owner, who still thought he was.  My preference was to go to Mather, which is where the maintenance facilities are, but the owner wanted to go back to San Carlos so he could score a commercial flight to Seattle (he still had a meeting to get to).  As an aside, if YOU hate traveling commercial, can you imagine how much an airplane owner hates doing so?

I coordinated with ATC, explaining that I had an engine problem, and I needed to return to SQL NOW.  ATC gave me direct SQL and wanted me to descend to 5,000, but with a flaky engine, I was thinking that altitude was my friend, so I asked to stay at 13,000 until I needed to descend.  I was at 13,000 over SFO, at which point, I can make the runway entering a right downwind for 30 even if the engine quits.  Surprise, they offer me straight-in on 12 (wind is variable at 3 Kts).  So, I initiated a “space shuttle approach” - full flaps, gear down, power idle and if it isn’t as fast as the space shuttle, it’s the same steep approach path.  From 13,000 feet at SFO, I was able to land straight in at SQL.  It’s kinda fun, actually.

At this point, we still don’t know what the issue is.  After a test flight with a mechanic (David Vital, former WVFC Chief of Maintenance), in which everything was completely normal, the maintenance folks are going to be chasing down a couple of leads, but until something stays broken, they can’t find the problem.

At this point, I usually have some kind of observation about things that apply to club aircraft, and most of this stuff doesn’t.  With one very serious exception: airplanes talk – they rarely yell, but they do say things – and pilots should listen, especially if what the plane is saying is different from what it normally says.

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