Encourage one another and build one another up. Pray without ceasing. Test everything. Keep what is good. Avoid all evil. -1 Thess 5:11,17,21,22
Thursday, April 16, 2020
Quest: Passing Inspection
Tory looked up from the page she was studying and asked “What is icing on a plane?”
Dot understood why she was confused. Dot had just put three, iced, maple ginger-snaps on a plate next to Tory for a snack.
Dot sympathized with Tory. It all made sense once you had all the pieces squared away in your head but until that happened it was a bunch of senseless mumbo-jumbo. The important thing, in Dot’s mind, was that Tory understand how the parts fit together.
“An airplane wing is called an air foil. When wind passes over and under it, it creates lift because the pressure is lower on the top of the wing than below it. It creates lift because the profile of the wing is very precisely cut.” Dot said.
Tory nodded her head. That sort of made sense.
Dot had shown Tory how the air blowing across the TOP of the wing lifted by holding a sheet of paper by one edge and causing the trailing edge to levitate.
“Air gets warmer under pressure and colder when it is moving faster or lower pressure” Dot continued. “If you are flying through fog or rain when the ambient temperature is at or just below freezing, that little bit of additional cooling is enough to cause ice to form on a wing and destroy its lift.”
Tory was still struggling. “Why would a little bit of ice be a problem? It can’t be that heavy. And besides, if the temperature is below freezing, wouldn't it be snow rather than water drops?"
“You are missing the point” Dot said. “The ice messes with the shape of the wing. If the contour changes too abruptly, then the air will not flow smoothly across it. It will separate or back-eddy and then you will stall.”
"And the point about liquid below water is that there are a lot of times when water stays liquid when it is blow 32F...fast running streams, for instance. Water needs a 'seed' to crystallize. The ice that is already on the wing is that crystal." Dot said.
Tory was frustrated. Too many new words. Too many concepts. She just wanted to fly.
“Don’t worry honey. It is hard for everybody at the start.” Dot assured her.
Later that day, Dot handed Tory the 25-hour, inspection checklist.
“This is one of the things you studied this morning. Let’s see how well you learned.” Dot said.
Tory took one, last quick look at the checklist and then started moving over the plane.
Five minutes later, Tory said “Done!”
Dot corrected her “I beg to differ. You haven’t even started.”
“But I did everything on the list?” Tory objected.
Dot had to handle this gently. It is soul-crushing to get roundly criticized but it was something Dot had to do. Safety is more important than coddling egos.
“If you had read the instructions, you would have known that you have to read the text out-loud, do one inspection and then check-off that item. That is why it is called a ‘check-list’.” Dot said.
When Dot realized that things were going in the ditch, she had made up a few copies of the check-list and had them laminated. She also bought a boat-load of common, black, wax crayons to write on the re-usable checklists.
“That is stupid!” Tory exclaimed.
“Did I ever tell you about my nephew, Joe Barbot*?” Dot asked.
Tory shook her head “No”
“Joe was a Straight A student. Joe was the first in his family to graduate from college. Got hired by one of the big three as an Engineer. In 1987 the company was flying him out to Arizona to the desert proving grounds.” Dot said.
“The pilot and the aircrew were in a hurry. They ripped through the pre-flight checklist and didn’t do the items one at a time. Somehow they missed the fact that the flaps...little wings that extend and give extra lift at low speed...were not deployed.” Dot said.
Tory drew in her breath.
“There was only one survivor” Dot said. “A four year old girl. Joe and a hundred-and-fifty other people died because the crew didn’t do the checklist the right way.”
“Every time you see instructions that seem complicated or take time, you need to realized that somebody died and those details were included to make sure that YOU and ME don’t die for the same reasons.” Dot said.
“So let’s take our time and do this the right way.” Dot said.
Since the plane had the foldable wings, the 25-hour airplane inspection and maintenance checklist had “Check bolt torque” for the wing bolts.
Tory said “They are fine.”
“I didn’t see you check them.” Dot said.
“We just put the wings on and you showed me how to torque them” Tory objected.
Grumpily, Tory got the click wrench and checked them. One of them was only finger tight, a fact that Dot knew because she had deliberately not tightened it.
When they got to the various pins, Tory made a big show of checking them. “Yup, they are all good.”
“Look at the checklist. What does it ask for?” Dot said, sweetly.
Tory took another look at the checklist. “Umm, says to write down a number.”
“So how many did you check?” Dot asked.
“All of them.” Tory insisted.
“How many was that?” Dot asked.
“Six” Tory said as she moved around the plane and counted them.
“What does the checklist say? How many does the checklist say you should have checked?” Dot asked.
Tory, once again looked at the list. Sheepishly, she said “Eight”.
“Well, you better find two more pins” Dot said.
Finally, Tory found the two ‘extra’ pins hiding in the wings above the fuselage.
“I don’t mean to be a nag, but you didn’t check the pins correctly” Dot said.
Tory rolled her eyes. Dot pretended to not notice.
“Pull one of the pins.” Dot commanded.
It came out easily.
“Take this rag and wipe down the pin.” Dot said.
“You should be feeling for roughness and rust and looking for cracks” Dot said.
“Why not just look at them?” Tory asked.
“Your fingers will catch problems you can’t see. Besides, the rag is dampened with oil that will make the pin easy to replace and protect it against rust. Win-win” Dot said
"What do I do if I feel rust?" Tory asked.
"If it is light, I have some 400 grit sand-paper to polish it off. If it is too deep to sand out, we replace the pin." Dot said.
"Couldn't we just use a power sander?" Tory asked. Her dad had LOTS of power tools.
"Nope." Dot said, aghast. "If the pitting is that deep then it is time to replace the pin."
The two women spent the rest of the afternoon slowly inspecting the plane to Dot’s satisfaction with Dot explaining the reasons for every tiny detail.
*One of the victims of the crash grew up in my old neighborhood a couple of years behind me. His name was Joe but I changed his last name for the sake of privacy. His family was Hispanic. All of the rest of the details are accurate.
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I think that most modern Americans don't work where a mistake in procedure can get you killed.ReplyDelete
Both Mother Nature and Murphy are trying to kill you all the time.
Over the years engineers have automated systems and implemented 'fail safes' to protect stupid people from themselves. A dumbing down of technology. Lots of reasons why, but the nth order effects of that engineering are that people will die when the fail safe stuff breaks down because the operators don't understand the system and equipment.ReplyDelete
The old Snap On red brick scan tools are a perfect example. A scroll wheel and a yes button and a no button. It was designed for operation by the lowest common denominator. The high school dropout with a set of harbor freight wrenches... I wish I had a nickel for every time I saw a parts changer throw parts at a problem to fix a frayed wire. I once bought a Subaru station wagon that needed an engine for $500. It ran just fine with a spark plug thread insert, a spark plug and a spark plug wire...
I see "TPM"s get checked off all the time with major failures the next day not uncommon.ReplyDelete
Fortunately it's only lost production.
Oh yeah, preflight IS critical... Friend of mine died going off the pointy end in an S-3. One wing. fold had not locked properly... four dead even with ejection seats. Less than one second from launch to in the water inverted.ReplyDelete