Steve1300

Actually, it is more like lack of training. Not everybody has the opportunity to attend a course that covers operational checks of the landing gear extension and retractions system, and they don't bother to read the technical orders until they really have to. People just "assume" that they know how things should be. I've seen some really great mechanics who can normally figure out complex problems who will become stuck on an issue merely because they don't read enough. The beloved FAA has approached this problem in their regulations. They do not allow an A&P to perform a task unless the A&P has been taught how to do that task. In short, mechanics are technically not permitted to "figure out" how to do a task; they must be trained first. I guess the FAA knows that many mechanics won't read. The funny part is that A&P's also assume that their license means that they can work on any aircraft they choose and do any job they want. The truth is that the A&P is merely a license to learn.

There is no reference for that. This is one of the oldest questions that I am aware of in the Herk world, and people will have opinions on both sides of the question. I have refueled aircraft with leading edges removed with no problems. I have also defueled aircraft with leading edges removed with no problem. Then again, I won a case of beer from a DCM when I installed a leading edge on a plane in fuel cell would not be used because the folks could not get the leading edge back on themselves. I don't know, though, if it was off when the plane was refuelded or defueled. Sometimes, stuff just doesn't go back on easily, no matter what you do.

Even on the ground, the aft cargo door is not required to be able to free fall down and lock. From a JG that I have: Using auxiliary hydraulic system handpump (3), apply hydraulic pressure. RESULT: On airplanes AF72-1288 and up, aft cargo door fully closes and locks at a pressure less than 1,000 psi. On airplanes prior to AF72-1288, aft cargo door fully closes and locks at a pressure less than 1,500 psi.

You didn't say whether or not you are troublshooting a problem based on your tach indicator or from RPM given by an accutach. If your problem IS based on your tachometer indicator, make sure it is accurate or you'll be chasing a problem that doesn't exist.

Hey, nice looking model you have there!

Have you ever tried to back an aircraft that was leaning out of a hangar? Try it some day and you won't have to ask the question - it will turn itself toward the leaning side. When towing one forward, it won't be able to force a turn because of the tug. If you taxi one that is leaning, you'll find yourself having to correct for the pull to the low side constantly. The more the lean, the harder the tendency to turn.

The is an interesting solution. Did you use the same gauge to measure strut pressures in all the struts or different gauges? I like to use hoses that are "Y'd" together and equalize pressure between the left and right struts at the same time, and those hoses go to only one gauge so that the pressure is equalized between the left and right struts. Unfortunately, with the pressures that we deal with and the inherent inaccuracy of gauges (the standard being one increment as a tolerance when calibrating gauges) it is possible to have 200 psi difference between the left and right side if one uses a cheaper gauge to do the work. It is expensive to have a strut pressure gauge with has increments of only 10 PSI in that range. In short, the possibility of error is built in to the system by the quality of the gauges we use.

Many things can cause that. If the aircraft is not leaning left wing low, and your MLG tires are not underinflated on the left side, and your torque indicators are correctly calibrated and even as you are taxiing, and your nose wheel steering is rigged to the center position correctly, then check for dragging brakes on the left MLG. Would it be a silly question to ask if you are having a constant strong crosswind?

I am aware of a case of Herks being on soft sand. In order to get the aircraft to "float up" onto the top of the soft surface, they had to pump the elevators while accelerating in order to lift up higher and get more speed for takeoff. If you are on soft soil or sand, you'll need lots of runway. Even then, once your MLG doors are plowing the surface, I don't know how much luck you'll have.

We have nothing in our manuals that prohibit that. I doubt that you'd find it to make the installation any more difficult.

I can get you block diagrams of the internal workings, if that is what you are after. It may be not till next week for me to do that, but I am sure that I have them somewhere. You have a PM.

Are you looking for the internal workings?

As for specific aircraft, I have no answer. However, there are at least two different types of landing light assemblies. One of them is the "High-speed" landing lights that permit their use up to 250 knots. I suspect that those Herks with the higher limit have those particular light assemblies.

This topic is very popular with our engineers. It seems that they are constantly bombarded with this "bad thermocouple" issue when at the simulator and at systems refreshers. While I agree that this can be a problem, unfortunately they don't ever seem to get told about the other causes of problems like this. Every "high torque" instance becomes a thermocouple problem. It is kind of funny, too, that we tend to get out the yellow box for low power write-ups, but that is a subject for a different thread. Good going on the indicator problem. You saved yourself a whole bunch of time.

Well, it is a bit more complicated than that. As far as from a pilot's perspective, it might seem that simple. Then again, even a pilot would need to be aware of whether the brakes were in normal or emergency. The power brake control valve (by the operators pressure on the tops of the rudder pedals) determines the amount of pressure to go to the brakes and the brake selector valves determine whether or not the pressure goes through the anti-skid control valve or not. Red October, would you want a pdf file explaining all this or is this enough?

I don't know that shimmy in the NLG is ever caused by just one problem area. Usually, there are two or more items that are "a little off" but together the result is a nose gear shimmy. If it happens on the roll, then first of all, the shimmy dampeners must not be able to compensate for it. The original reason will be something else, whether it is a scissors bushing problem, a nose tire problem, nose bearing problems, etc, etc. Conversely, we can frequently eliminate a shimmy for a short while just be fixing one of the problem areas, and I fear that is what we usually do. If I have a shimmy on takeoff or landing roll, I always bleed the air out of the steering actuators to allow the shimmy dampeners to do their job. Like scissors bushings, that is a pain so many folks either don't want to do that or they won't do it thoroughly. In addition to that, I try to find out why the shimmy occured in the first place. Nose gear tires are allowed to be of different diameters by only 3/8th of an inch. It is not easy to measure on the line and should have been done before installation. Most folks want to disregard the scissors bushings as they are a pain to change out, so worn out bushings are fairly common. If you have aggressive operators who like to taxi fast and make 90 degree turns, you will eventually get out-of-balance tires where they were skidded sideways. The only way I have been able to check them is to slow roll them when the nose is jacked up off the ground. I've had them either stop in the same spot most of the time, or I have had them stop and reverse direction of rotation all by themselves. However, even then, it usually takes another condition to permit the nose gear to shimmy, and I find that worn scissors bushings is the other condition. The shimmy dampeners can't work well if the nose gear is "loose."

From the time that we arrived on base until we left, an outer wing replacement took two to three weeks. The outboard engines were removed prior to our arrival, but the wings were installed and the engines back on and all checks completed before we left. Keep in mind that we were a military team, so things like weekends and overtime was not an issue. Inboard rainbow fitting replacements are a different story.

I can tell you that, when I was travelling on wing change teams for WR/ALC, we had work packages to follow. After we removed the wings, special two-man teams would come out and do a "planarity check" on the rainbow fitings and then realign the fittings by milling down the nodes that extened too far out in the plane. They also gave us shimming requirements for when we mounted the wings back on. Once the wings were reinstalled, a team would come back using optical tools and tape measures to check the alignment of the wings. It was more guided than the instructions that we have in our maintenance manuals.

Maybe, but it is not listed in the aircraft IPB or the Allison IPB. Apparently, it does have something to do with a vacuum cleaner.

I would guess you are referring to throttle and flight control cable tension regulators? Ours are due every three years for a special inspection. If you would care to PM me with an email address, I can send you some information.

SZYOUD, your question is not in reference to the original post, correct? We are discussing a different aircraft now? This 70 PSI is with no bleed air load? If we are on a different aircraft and problem, this should probably been less confusing if it were a different thread. Assuming all answers above are a "yes" and that you have an aircraft that shows only 70 PSI on the manifold pressure gauge with all four engines running and the bleed air regulator valves in "override," then I wonder if your airfield is a very high altitude one. Are you in Caracus? If you are not at 13k feet airfield elevation, then you do seem to have a problem. Inside your horsecollars, you should have a bleed air duct that has a tap-off where you can hook up a good direct pressure gauge. I'd suggest that you put a gauge on one of those ducts and see what the pressure is from the other three engines (one at a time). IF you still get only 70 PSI (since you claim that your bleed air manifold bleed-down time is 10 seconds AND you do not have a newer model Herc that requires more time than that) then you have four bad compressors. (You can also hook a hose up to the pressure test fittings on your compressor diffusers to see what your compressors are actually putting out.) Seeing that four bad compressors is a bit of a stretch, I'd be looking under the flight deck and behind the Nav's station for a broken bleed air line that goes to your manifold pressure gauge. That very small line - if broken or cracked or if you have a missing cap on a "T" fitting somewhere - will not cause a bleed down check to be bad, but will cause your manifold pressure to read low; that is what I'd hope to find. I hope this helps. Let us know what you find, please.

Well, as one who did not wear a baggy zipper suit, I can tell you that MAC was a major step down for "crew chiefs." While in TAC, crew chiefs actually used their tool boxes and were expected to. I cam back from Thailand in 75 and found my unit with MAC patches. The shock I had when I went to the flight line and discovered that I am now a professional seat rigger instead of being a mechanic was awful. Somehow, MAC had no concept of Herk operations or the need for qualified mechanics with tool boxes deployed in remote locations. I guess they figured enroute stations would handle everything with specialists. It may have been great for those who had seats in the front of the planes, but for those of us who signed up to be Herk Mechanics, life took a major step down. We were so busy rigging for pax and pallets, we didn't have time to be mechanics any more. I went to CBPO and volunteered to go overseas and get out of MAC right away.

Here is what our inspection cards say about this check: ________________________________ Transient Governing Response Check. (l) Mechanical Governing - With the propeller governor switch in MECH GOV. advance the throttle from FLIGHT IDLE to TAKE-OFF in four seconds. RESULT: With steady winds of 10 knots or less, the over-speed should not exceed 106 percent. The (accurate tachometer) engine RPM should recover to within 100 (+1 percent) within 30 seconds from the end of throttle movement. NOTE: If it has previously been determined that a TAKE-OFF position, the torque limit is exceeded, use 17,000 inch-pounds torque as indicated on the tachometer for both governing checks. (2) Normal Governing - With the propeller governor switch in NORMAL, advance the throttle from FLIGHT IDLE to TAKE-OFF in four seconds. With a steady winds of 10 knots or less, the over-speed should not exceed 104 percent. The (accurate tachometer) engine RPM should recover to 100 (+1 percent) within 15 seconds from the end of the throttle movement. ________________________

From a Lockheed Training manual covering the engines: Downstream from the firewall shutoff valve is the fuel heater and strainer assembly. It utilizes an oil-to-fuel heat exchanger. In the heat exchanger, fuel is warmed to prevent icing in the strainer. The fuel temperature is sensed by a thermostat after the fuel has passed through the heat exchanger. The thermostat is connected to a modulating valve. This valve controls the flow of oil through the heat exchanger. The oil passing over the tubes of the heat exchanger gives off heat that is absorbed by the fuel as it passes through the inside of the heat exchanger tubes. The heat exchanger is capable of raising the temperature of the fuel from a possible temperature of -700 F at the inlet to a minimum outlet temperature of +340 F. A 200-mesh screen wire strainer is provided in the outlet section to collect solid particles that may be in the flowing fuel.

To clarify the problem, let's see if I can restate this more in the terms that I think of this system: At approximately 72%, everything seems fine - even if left at 72% for a couple moments? However, when brought to approx 97%, torque moves from the normal level of 1200 pounds or so momentarily and the climbs up to a value that overloads the engine and RPM decreases to 94%. The only apparently influence that causes this is RPM? Somehow, hydraulic pressure is getting out to the dome and pushing the blades to increase pitch - but only at normal ground idle RPM. The normal increase-pitch pathway of fluid has been replaced (valve housing). The normal source of this pressure fluid has not (pressurized sump and pump housing pumps). Is it possible that there is a crack (or check valve) in the pump housing that allowed pressurized fluid to make its way into the side of the dome that increases pitch - as in a backflow of some sort? I think I'd be removing the pump housing and applying a strong light and magnifying glass to this pump housing. Somewhere, the return fluid from the dome may be backing up the return fluid from the dome and actually pushing fluid to the dome. I say that only because the other sealed areas that separate pressure fluid chambers has already been replaced. I definitly would like to know what you find. I may never see it or hear of it again, but I might remember this one for a long time.