Pelican's Perch #75:
Those Dreadful POHs (Part 1)
Everything your POH says is correct, and anything it doesn't say you can do, you can't, right? Did you really think John Deakin -- AVweb's favorite contrarian -- could let that kind of gross generality continue unquestioned?
"And the Lord spoke again unto Moses from the burning bush, and said, "Get thee up the slopes of Mount Sinai yet again, and there I shall cause to be written in stone a whole host of tablets. These tablets shall each bear a name that will be strange unto you, such as Piper, Beech, Boeing and Mooney. Thou shalt preserve and protect these tablets forever, and no one may ever alter them or deviate from them, for they are the truth, the light, and the only way."
Nope, I can't find that in the Bible, or anywhere else either, but from the way most pilots talk, you'd think that was indeed the origin of any of those documents with various names such as "Pilot's Operating Handbook," "Operator's Manual," or the "Dash One" (military).
Ah, if only it was true, and we could be sure "The Written Word" was true and correct when it comes to these documents.
Folks, I'm sorry. There is no Santa Claus, no Easter Bunny, and no Tooth Fairy, and aircraft operating manuals by any name are written by humans, with human failings, often with agendas of some sort, usually with marketing in mind. The humans who take on the evil chore of doing a manual are often at the bottom of the totem pole of knowledge, skill and experience at the factory, and when they are through, often the lawyers take over to do the old CYA act, and few of them are pilots.
The results range from utterly useless to minimally acceptable. There are always errors, or there wouldn't be revisions.
And no, Virginia, the FAA doesn't pay much attention to the "how to" part of manuals, and thank goodness for that, for if they did there'd be yet another layer of bureaucracy and incompetence on top of what we already have.
A Limitation? Or Limited Liability?
In fact, the only part of any manual (GA or airline) that is "FAA-Approved" is the section on "Limitations." (Often, there will be verbiage in "Limitations" that requires the use of "Performance" -- usually a separate section. Without that language, "Performance" is also "informational only.")
When required by "Limitations," the FAA does review that data, and in some cases for the "big iron," FAA test pilots will actually fly the airplane on some of the certification flights. At the highest levels (Boeing), these are some pretty competent people, and the hard engineering numbers that come out of these tests and that level of scrutiny are really very good.
But as you work your way down the food chain, the skill and talent levels drop off, both at the FAA and at the factories.
Take the argument over the use of flaps for takeoff in the Bonanza. Early POHs described this procedure, and had data for it. Later manuals omit any mention of flaps for takeoff. Why? Did something about the airplane change that made flaps less effective, more dangerous, or undesirable? No, the wings, flaps, and part numbers were the same.
If we get right down to the nitty-gritty, either the early procedure to use flaps was wrong, or the later procedure not to use them is wrong. To my knowledge, there's never been a comment from the factory on the change, or why it was changed.
Can I guess? Sure. I think the lawyers got into it, and pointed out that by including the procedures and data for takeoffs with flaps, Beech was creating a liability risk if pilots misused flaps. It also took time and money to develop that data (expensive additional certification flights), more lawyer-hours to proof it, and more paper to print it. Finally, it's a rare case when simple flap systems are much help on takeoff. They may well give you a shorter takeoff roll (where full flaps may be best), but in general they'll cost you a lot of climb performance. At higher elevation airports, the use of any flaps at all can prevent flight, and put you into the rocks.
I think a legitimate argument can be (and probably was) made for omitting the procedure, and I don't have any heartburn over it. What gives me heartburn are the people who say, "Takeoff with flaps is illegal, unless it's in the manual." Absolutely not true, unless it's in "Limitations," with language like "Takeoff with flaps is prohibited." Now that's something you can hang your hat on. If that sort of language is in "Limitations," and an FAA type sees you use them for takeoff, he's got a legitimate bust.
A Story ...
When I joined Air America in 1963, they used the old military "Dash One" manuals for most of the airplanes. These are pretty good, I think. I've always liked most of them. They cover the systems with good detail; often have wonderful color schematics, and a minimum of procedural stuff, for they are very simple airplanes. I have no experience with any military manuals written after about 1954, so I don't know what I'd think of the modern military manuals.
One exception was the horrible Air America manual for the "Twin Beech." We had a number of different models, a real potpourri, from the straight old military C-45 with a max gross weight of 8,750, to the "Conrad Ten-Two" conversion, with a gross of 10,200. Later, "The Company" would convert almost all of them to the "Volpar," with two turboprop engines.
The "manual" for the airplane was the worst I've ever seen. It was full of typographical and systems errors, described airplanes we didn't even have, was badly organized and poorly printed, a real mess.
I made a few comments to the chief pilot, and his response was, "Yeah, yeah, drop me a note with your comments." I was too young and dumb to realize that was a brush-off, and the last thing on earth he wanted was "extra work." I sat down and typed up 27 pages of single-spaced text for him. I doubt anyone ever got past the first paragraph, and I'm positive it hit the wastebasket within 30 seconds. My friends got a huge laugh at my expense, and "What did you expect, stupid?" Color me na´ve; I thought a good, short, clear manual for our specific airplanes would be a good thing.
Another Story ...
With pistons and props, especially on the old airliners, there is a device known as a "friction lock." This was used because the constant vibration would actually move the engine controls, and some of those controls suffered backpressure or spring-pressure that tended to move them in undesired ways. Sometimes those friction locks wore thin, and didn't quite do the job, and sometimes a small engine burp might close a throttle at an inopportune time. It became the standard practice for one crewmember to "guard" the throttles to prevent this from happening. We still see this today, with flight instructors stressing the need to keep one hand on the throttle at all times. That's not exactly a bad procedure, but I think they overdo it just a bit. Yeah, yeah, I know, it's for an abort.
On airplanes with Flight Engineers, this "throttle guard duty" fell to the FE. The flying pilot would get takeoff power nearly set, then lift his hand from the throttles to allow the FE to fine-tune the MP setting, then the FE would drop his hand to the bottom of the levers ("backing them up") where they disappear into the pedestal, while the pilot put his hand back onto, and held the throttle knobs. This also served as a universal signal that "I'm gonna stop if an engine fails." At some point (V1, if there was one), the pilot would make a distinct move off the throttles, and this is, even today, the universal signal to everyone in the cockpit, "I'm gonna keep on going with an engine failure."
Then the jets came in. There is no vibration to move thrust levers, and there is nothing at the engine that will move them improperly. Some installations have "throttle snatchers" for various purposes, and frankly, you don't want your hand anywhere near the levers when those actuate!
But tradition dies hard, and the "Flight Engineer Culture" is hidebound. Few were able to wipe out years of custom, and most argued to just continue the old ways: Pilot shoves the thrust levers up, FE fine-tunes, pilot puts his hand back on to V1, while the FE "guards" them. A little extra work, but harmless, and it wasn't worth hurting the FE's feelings, or making him feel unneeded. Feelings are important, especially when your lifelong career is slowly going away.
Make no mistake: I love having an FE on the big, complex airplanes. A good FE is worth his weight in gold, and more so when there's a systems problem. I'm not sure we improved the industry by automating most FE functions and doing away with them. I think that was an economic matter, not necessarily a good idea from an operational standpoint. But it's done.
On the other hand, a bad FE can be a nightmare, as we shall see.
Entrenched FE Culture Meets The Jumbo Jet
|B747 Thrust Levers (click for larger version)|
The 747 came out with something new, or at least I'd never seen it before. About halfway up the back of the throttle levers there was about a 3-inch stub sticking back, with another knob, just for the FE. In those days, the "Flight Engineer Culture" was very strong at Japan Airlines, and it often seemed that the old FEs had more authority than the captains, particularly when it came to anything involving engines or systems. The industry was also moving to "Second Officers," moving young pilots into the FE seat with very little in-depth engineer training. The crusty old career FEs resented this program greatly. The Japanese are often inscrutable, but mention "second officer" to an old Japanese FE, and they got "right scrutable, right now."
A side issue, here: I started out on the 727 with JAL, and Boeing called them "Thrust Levers." At JAL, one dared not slip and call them "Throttles," or it was a bust, because "the (holy) book says 'thrust lever.'" Then I moved to the DC-8, and Douglas called them "Throttles," so one dared not slip and call them "Thrust Levers." Then back to the B-747, and back to "thrust levers." JAL was not the only airline with this problem. Now if the FAA were so omnipotent, don't you think they could at least standardize on this simple thing? No, they don't care. Around the world, many airlines standardized the term across their fleets, and changed their "books" accordingly.
On this giant new and magnificent airplane the old Japanese FEs moved quickly to establish their usual dominance over anything related to engines and systems, and soon "the book" said that pilots should get the thrust up to nearly takeoff thrust, then relax that hand a bit and let the FE "fine-tune" it, then the pilot would hold the upper knobs for a rejected takeoff. ("Abort" became politically incorrect, and Boeing developed the term "Reject" instead. I suppose they were worried we were going to start performing abortions in the cockpit, or something.)
Only trouble was, those old FEs loved those extra knobs, and once takeoff thrust was established (before 80 knots), they'd take a death grip on them and hang on for dear life until reaching 1,500 feet AGL, and setting "Climb Thrust." Only then would they let go.
I hated this from the start, on three counts. First, it would make an abort more difficult, because the pilot would have to overcome the initial resistance of the FE. Second, I was nervous about the FE's seat releasing and sliding back about three feet with the steep deck angle. Third, I was afraid that any sudden noise or vibration would trigger the FE to instinctively pull the thrust levers back, possibly at a critical time (like rotation). This was made worse by the philosophy in those days that the slightest abuse of the engine would cause it to instantly blow up, so everyone was spring-loaded to pull that thrust lever back if something wasn't right.
("Palm 90," the Air Florida crash on the 14th Street Bridge in Washington, D.C., changed all that, but too late.)
I wrote a few letters, but JAL doesn't pay any attention to anything said or written by "gaijins" (literally, "aliens," or "outsiders"), and the letters accomplished absolutely nothing except further ridicule from my friends, many of whom had come over from Air America after me. I briefed the FEs on every takeoff to please not grip the thrust levers, and I explained why. Some saw the logic and adopted it, some protested that it wasn't "according to the SOP," and a very few refused to comply. My case was enhanced in the next few years, when JAL had two cases of "seat release," and the FE slid back abruptly at rotation, taking the thrust levers back with him. Fortunately, both were domestic flights, light on fuel, and when the throttle hit the aft stops, the FE's hand was pulled loose, and the pilots were able to shove the levers back up again. Had it happened on a loaded trans-Pacific flight, I'm not sure the outcome would have been so favorable.
I wrote more letters that were ignored, to more ridicule. JAL finally adopted a procedure where the FE would brace himself with his right arm behind, pushing on the table, and his left hand on the FE's throttle knobs. (The seat probably weighs 200 pounds or more, plus the FE's weight. I wonder what good bracing with one arm will do?) They also stated in the book not to "grip" the knobs, but to set them, then "touch" them with fingertips only, ready to make adjustments as needed.
While this was an improvement, I still didn't like it. (I was such a pain in the you-know-what, in those days). I always asked my FEs to please adjust the thrust before 80 knots, then just take their hands away from the thrust levers entirely, even fold their arms. If they needed to make a further adjustment (the "book" clearly forbade any adjustment after 80), then reach forward with one finger and make it.
This worked pretty well, except for a very few crusty old chief flight engineers, who thought the original method was the only way, and they would take the old death grip, in spite of my pointing out "the book." Fortunately, these old, hidebound, stubborn (and mostly incompetent) people usually stayed in the office, leaving the flying to lesser mortals, only doing a trip for some currency requirement.
It fell to me to have the worst one of all on a 747 cargo flight from Tokyo to Anchorage, to New York, back to Anchorage, and back to Tokyo, with an overnight for the crew at each location. I briefed him in Tokyo, and he used the old-style death-grip. We talked about it on the way to Anchorage, and he dismissed my words with disdain. It didn't help that he was nearly 60, and I was a mere 35 or so. I tried again in Anchorage, and again he ignored me with outright contempt. I tried again in New York, and this time made it a direct order. "You don't have the right to make that an order." I debated just returning to the ramp for a crew change, but I figured a "gaijin" wouldn't stand a chance in the ensuing brouhaha, so I bit my tongue, and decided I'd fight the battle when we got home, and simply refuse any further flights with him.
The copilot was brand-new, very young, and a very nice fellow, with perhaps 500 total hours (he is a very senior captain, today). He knew and did his job well, but was a bit wide-eyed at the ever more hostile interchange between me and the blockhead behind us.
It was a 3 a.m. departure on runway 22R at JFK, which ends in Jamaica Bay. Good weather, but it was a dark, moonless night, and it's a "black hole departure" at the best of times. No matter how many times you do it, it's a fairly disconcerting takeoff when the nose comes up, the runway lights disappear, and you're suddenly and totally on instruments. The few distant lights just make it worse.
And that's just when the engine blew up.
I am reminded of that line in "Casablanca," when Bogart says something like, "Of all the gin joints in all the towns in all the world ... she walks into mine."
Of all the airplanes, with all the pilots, and all the takeoffs, that dammed seagull had to pick the one flown by the one pilot who was making a stink over this issue, with the worst FE in the world working. Fate was truly the hunter that night. It must have been a big gull, and he hit precisely on the tip of the "bullet," the big spinning nose cone in the air intake of number four engine. That nose cone opened up like a flower, and the near supersonic airflow ripped it apart and flung it right through the engine core. It took out some of the fan, most of the compressor and almost all the turbine, causing the classic "Uncontained Engine Failure." All these engines have protective armor to prevent a few blades and parts from going anywhere, and all will survive even a fairly large bird passing through the innards. They may fail, and parts may come loose from the shaft, but they should not make holes in the cowling.
None of them will contain a failure of this magnitude. There was a huge explosion that sounded like a 12-gauge shotgun in the cockpit. The whole airplane shuddered, and the flash lit the whole airport. A friend in the tower later told me he thought it was a bomb from the sound that rattled the windows, and from the flash, which blinded him for a few moments. We later found gaping holes in the cowling around both the nine-foot diameter fan and further back, around the turbine.
A Deer in the (Panel) Lights
We were passing about 200 feet when the seagull committed suicide, and you might say it got my attention. Engine failures are very, very rare in the jet world, so my first thought was, "Why me?"
|B747 Center Panel (click for larger version)|
One of the "cute" design features of the classic 747 is that all the engine instruments go clickety-click when they are changing, and any one of them in motion will be heard by all on the flight deck. Not loud enough to be obnoxious, but very useful as an aural cue. There are four instruments across, and four instruments high and all 16 click when the needle is moving. Fail an engine (usually in the simulator), and four instruments go clickety-click -- a real attention-getter.
Right after the engine blew up, I felt a huge thrust reduction, and I heard all 16 engine instruments clattering down, sounding like a roomful of castanets. A quick glance confirmed that all four engines were spooling down as if all had failed. I was really puzzled, because that just doesn't happen. Then I looked down, and saw the thrust levers well back from the normal position, and the FE's hand, still with a death-grip on "his" knobs. Just exactly as I had been predicting for years, he had flinched, and jerked them all back unconsciously. I almost had to break his wrist to get his hand off them, and then it was an easy matter to shove all four back up and continue. The rest of the flight was a routine, three-engine, lazy 270-degree left turn around to runway 31R. It was entirely up to the two of us, because the FE was in a state of total shock, unmoving and open-mouthed, unable to even read the before-landing checklist. He barely managed to read the shutdown check.
We spent an extra day in New York while they changed the engine and patched a few shrapnel holes, and finished the trip to Tokyo. The old FE was still angry and bitter, but at least he kept his hand off the thrust levers, this time.
He later lied, and said he'd never pulled the thrust levers back at all. Fortunately for me, the young copilot told the truth, and confirmed my story. I never flew with that FE again. Months later, the much-revered chief pilot found me in a quiet room all alone, and said, "Deakin-san, I've read all your letters, and I agree with them 100%. I read about your incident in New York, and I think you did a very good job. Please keep up the good work. But you must understand that the cultural problem with the old FEs here is very difficult, and change will be very slow." And he walked away. "The Book" never did change, to my knowledge.
The Blessed Book
There's a point in there somewhere. "The Book" was dead flat wrong. The original procedure was wrong, describing a very bad procedure. With all the expertise available, and with the best of intentions, cultural differences crept in, and polluted "The Book," making it less than it should have been. It got partially corrected, but years later. And this is one of the best "POHs" I've ever used!
Modern-day General Aviation POHs are the pits, mostly, and that's nowhere more evident that the parts that refer to engine management. By and large, the data in the back of the book is from "the old days," when there were engineers working at the factories. The power charts resemble very closely the old power charts on the big radials. Many of the charts will have an example problem superimposed, and these can be very useful, with a little study. Unfortunately, very few study this data (or even know how to), preferring instead the third-grade language in the front that purports to tell the pilot how to do it.
All that said, there is some good information in some of them. As pilots, it's up to us to read them, put them together with information from experience, discount the worthless stuff, and add to the good. Pay attention to the limitations, and study the old engineering stuff in the back of the book, or in the engine manufacturer's book. Watch out for the text in the front.
Next month, I'll dissect a couple of these "modern" POHs. All have major errors; many have major contradictions in the same manual, or contradictions with the same engine in another manual, or just plain bad data.
Be careful up there!