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Aero Precision provides OEM part support for military aircraft operators across more than 20 aircraft

ShadoFE

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  1. Hey everyone, I’m looking for some info on the Copilot / AC Inst & Eng Fuel Cont inverters. Can anyone provide a rundown of which aircraft have solid state inverters vs. motor inverters? Which position are the inverters operated in for flight? Any ideas as to why some aircraft were with motor inverters were updated and others were not? What maintenance is required when converting inverter types? Thanks for any info you can provide.
  2. Thanks for the info. I think what tenten wrote sounds like what I had heard about. Not much to it really…just good common sense. I though it might give some guidance on some specific operating considerations beyond a daily fluid level and leak check. Like the following thought… So, when operating in this condition, is the prop low oil warning circuit disabled or does the light remain on during the flight? If memory serves me correct, there is only one circuit breaker which provides power to all four warning light and master light circuits. So, I can’t just pull the breaker for that engine and extinguish my flight deck warning lights without rendering the other warning lights inoperative as well. I would think that disabling the individual circuit to enable the master light to function as intended would be optimal. What would be the best way to do that? Simply disconnecting and securing the cannon plug on the engine seems simple enough, but I can’t remember if anything else is on that cannon plug that I wouldn’t want disconnected. Can anyone verify?
  3. Hey all, I’m hoping some old Herk operators can help me locate some long lost information. It happens from time to time that an aircraft is away from home station and qualified maintenance when the old prop low oil light comes on while on the ground. This scenario usually has but just a few possible outcomes. The FE checks the servicing and… 1. The prop is a couple quarts low due to a slow permissible leak or lack of proper servicing. In the end, the FE services it up and off they go. 2. The prop is a couple quarts low and leaking beyond acceptable limits. They’re broke and require a prop/seal change by qualified maintenance. 3. Surprise! The prop is properly serviced. Possible bad float switch in the pressurized sump. At this point the FE has all they really need to know…the prop fluid is not low. However, maintenance will usually ask the FE to disconnect the cannon plug to see if the light in the flight deck goes out. If it goes out, this confirms a bad float switch, if not, further troubleshooting will be necessary to find the trouble. Likely a short to ground in the wiring. It is scenario three I want to focus on. If the prop is not leaking, properly serviced and a bad float switch is confirmed, decision makers at the appropriate level must evaluate the risk of flying the aircraft home. Recently this scenario played out and when discussing with the O-6 about whether or not to return the aircraft, I was told that years ago (10+ yrs) there was a written procedure in the flight manual for operating the aircraft with a known bad float switch. This was news to me. I’ve been on Herks for about 10 years now and I’ve never seen anything in print about flying with a bad float switch. FE’s have always just applied systems knowledge and it has just been passed from one FE to another. Anyone out there know about this long lost written procedure? If so, please let me know. If not, what do you think it could possibly consist of? Thanks!
  4. Sorry for my delayed response. I was without internet for a few days. I agree that gross weight is a factor. However, I disagree that it solves this mystery. Consulting the CDS Flap Setting Chart I provided in an earlier post, we can see that the gross weight variable is accounted for. The flap setting is increased for an increase in the number of bundles at ANY given gross weight. An example... 130k lb Gross Weight and at a drop speed of 130 knots - with 1-4 bundles we use 17% flaps, 5-10 bundles uses 25%, and 11-16 bundles used 31%. So as we add bundles we add flaps (lower deck angle). 17% - 25% - 31%. This is all at the same gross weight of 130k lbs. So, yes, gross weight is a factor... We can also see from the chart that as the gross weight increases (number of bundles remains the same) the amout of flaps required increases. This is what you explained, and I agree. But a 130k lb airplane uses different flap settings when it is loaded with 2 bundles or 12. As long as the aircraft operating weight, fuel and number of bundles * bundle weight = 130k, the flap setting is determined by the number of bundles. 2 or 12...as long as it all adds up to 130k we would use different flap setting for each case. So I think the mystery continues. Ideas? Or am I mistaken?
  5. Thanks for your reply; a Loadmaster may be just the right person to solve this mystery. Initially I provided myself with the same logic you have presented, however; I have to consider a few situations in which this explanation does not seem to hold true. Situation 1. I naturally assumed that more bundles would mean more weight. But I must consider that I could potentially have 4 bundles weighing 1000lbs each or I could have 6 bundles loaded each weighing 500 lbs. (4 * 1000 = 4000lbs vs. 6 * 500 = 3000lbs) Why would I drop a heavier load at a higher deck angle? Again, the numbers here are just examples; there are many possibilities. I’m just showing that more bundles don’t necessarily mean more weight. Situation 2. Also, consider loading 16 bundles (8 per stick). I’ll have two separate rows of 8 bundles. If I drop one stick at a time, 8 bundles, I would use a flap setting for 8 bundles. However, if I drop both sticks simultaneously I would use a flap setting for 16 bundles. (Higher flap setting/lower deck angle required) I’ve attached a .doc file containing the CDS Flap Setting Chart for reference. As a result, I’ve determined that the weight of the bundles is not the determining factor…but I don’t know what is. I thought, then, that positioning (Fuselage Station) of the bundles must be the key. However, situation 2 makes that hard to prove. So I’m at a loss. Any thoughts or ideas are welcomed!
  6. A question came up around the squadron the other day. Let’s say we have five CDS bundles loaded, but we’re only going to drop two on this pass. When we choose the CDS flap setting, do we use the column for 5 bundles or 2? The numbers aren’t important. The question really is… Do we use the number of bundles loaded or to be dropped? Most importantly, why? Keep in mind, looking at the CDS Flap setting chart, more bundles require additional flaps. This means that more bundles require a lower deck angle. I have my own opinions on these, but I’ll keep them to myself so I don’t bias the responses.
  7. Thanks for trying this out! I think this definitively answers the original question…. Q. What does the emergency brake valve look/feel like when it is engaged? A. It looks like it always does! The lever is pressed hard right anytime the utility system is pressurized. It seems there is no way to visually determine if this valve is energized.
  8. This is a great idea. I wonder if I can talk the guys on the line into it. If so, it won’t be anytime soon. If I get a chance I’ll report my findings. If anyone else finds a chance please do the same.
  9. Thanks for the replies... I'm seeing that the answers so far fall into one of two categories... 1. If the valve is "hard right" it is set. (This is what I believed for about 10 yrs. I believe I've now found this to be false...I've found the valve to be "hard right" during normal operation. Either something is not working correctly or I've been wrong!) 2. There is no way to visually verify the position of this valve. Attempt to move the flaps via another method to confirm. (e.g. hydraulic override) The theory here being IF the valve is energized it is bypassing all fluid away from the flap selector valve and applying 3000psi to the emergency flap brakes. Now both sets of flap brakes are engaged to hold them in place. No pressure will be available to the flap selector valve...so if nothing happens...the valve is indeed set. Also, to take it one step farther, even if someone were to pull the manual drive engaging handle this would only disengage the normal spring applied brakes leaving the emergency flap brakes applied and the flaps still should not move. To put it simply, if the valve is energized the flaps WILL NOT move by any means. If it is not, the flaps will move via the normal manual override procedures. I agree with this method, however, I have a few trouble spots to get past. 1. The flight manual clearly states that if the flaps stop moving before reaching their desired position you are to "position the flap lever to correspond to the position of the flaps and NO FURTHER INFLIGHT MOVEMENT OF THE FLAPS SHOULD BE ATTEMPTED" (Probably not written by a FE!!) 2. Did someone REALLY design this valve with no means of visually determining whether or not it is set or not!?!?!? (poor design if that's true) Let me be clear, as the FE, I have no trouble trying to move the flaps to verify if the emergency flap brakes are set. I understand that IF it is set...nothing will happen...good or bad. If it is not and the flaps stopped moving due to another electrical malfunction...then we get our flaps back and there will be much rejoicing!! On this particular day I did recommend to the AC that we try just that. However, we were close to home with good weather and plenty of fuel so he preferred to just not mess with it. Sound logic I felt no reason to argue with. I sure hope there is a way to visually determine if this valve is set or not. If not, be prepared to explain your systems knowledge to the AC because they will not want to attempt further movement of the flaps. Thanks again for the discussion!
  10. The lever was found to be "hard right" with "no free play" in flight during the malfunction. After landing we have to shutdown before MX can board (part of the radiation checking procedures here for the Japan earthquake relief) but power did remain on. When I did make it to the back again after shutdown (power still on) the valve lever had its usual preflight "free play". (someone may have reset it before I got there) As soon as MX tied the ground test valve and turned on the aux pump the lever shot to the right and had no free play anymore (just as it was in flight), but the flaps ops checked good. This is what has me questioning what I thought I've known all along. I'm not suprised the flaps ops checked good, flase asymetric indications do happen sometimes. I'm just suprised the valve was "hard right" again. I've always thought when the valve was hard right with no free play anymore...it's engaged and must be pushed left to reset it. If that was true then I just watched the flaps move with the emergency flap brake "engaged"...with would indicate a bad emergency flap brake...but it DID work in flight by stopping the flaps at 40%. Soo...I don't think there is any malfunction here...I just want to be sure I know what I'm looking for when checking the lever during a malfunction because these things have a habit of coming back if water is not involved. How "stiff" is the lever suposed to be inflight when it is unset vs set?? When I check it I'm just seeing if there is any free play (like preflight). I don't use much force because I don't want to acidentaly reset it in flight. Thanks again for the help!
  11. Ok, I have a question regarding the emergency FLAP brake valve. After takeoff the flaps stopped retracting at 40%. C/B checked good so I went to the emergency flap brake valve. (Don’t worry I didn’t reset it). The valve reset lever was full forward (to the right when looking at it) and had no “free playâ€. I took this to mean it was engaged, however, after shutdown MX ran the flaps through and the valve was in the same position…flaps working fine. (FYI, water in the switches was not a factor) My question is… What does the emergency brake valve look/feel like when it is engaged? Thanks for the help!
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