Forum Replies Created
-
Posts
-
Sorry Bob, I missed the 76-62614. I thought that I remembered the flaps had pushrods but then couldn’t find them in the catalog yesterday. I just looked again and they’re damned hard to see (eyes getting old, I guess), but I finally found them and pulled up the drawing.
Anyway, Univair sells an REP5H unthreaded male rod end for Stinson 108’s that may be the same as the RE3H5, but they’re a whopping $85.75 each! Same price at Aircraft Spruce who also lists an REP3M6A, also for $85.75 that could be the same as the RE3M6A in our catalog. The AN201-K4A bearing that is staked into the 76-62304 rod end is also sold by Aircraft Spruce as AN201-KP4A (MS27641 series). I’m not a big fan of AS on account of their prices, so if they have them, somebody else probably has them too.
The Univair GMM-3M-680 for the Stinson 108 may also be the same as the RE3M6A , but I’m not sure. Their price is $26.50, which is at least bearable.
It couldn’t hurt to try Earl Allen who parts out Stinson 108’s in California (advertises in Barnstormers). Last time I spoke with him on the phone two years ago he had stripped 50 airframes so may have a large collection of usable 3H5 and M6A rod ends for considerably less money. Just a thought.
JG
Hello Bob,
Could you be more specific? There are…
A) The 76-62302 long push-pull control rods for the ailerons that go all the way into the fuselage, with a Stinson 76-62303 fixed outboard rod end and a 76-62304 adjustable inboard rod end, each containing pressed and staked bearings,
B) The short 76-62305 aileron push-pull rods that go from the ailerons to the bellcranks, of which there are two varieties with either the Fafnir RE2-M6A (early) or RE3-M6A (later) bearings.
C) The AN200-K3 bearings inserted into each flap bellcrank (aren’t any flap rods).
D) Something I haven’t covered?
Thanks,
Jim
Bill,
I just came across a copy of the original military W&B data report for L-5E-1 s/n 44-17922, dated June 11, 1945. The empty weight was 1,604# including oil, 8.50 tires, and all fixed and removable equipment except the canvas covers and pyrotechnics kit. The CG was located at 13.76″.
If the other “furnishings” are taken out that the military included in their empty weight calculation (tool kit, tie down kit, microphone and headphones, data case, report holder, message container, checklist, fire extinguisher, stowage box, misc. equip. bag, sun curtain, crash pad, first aid kit, and mooring kit), we can subtract 34.6#, giving a true empty weight of 1,569.4#. That’s still 15# heavier than where you’re at and the difference is probably accounted for in the original radio package that weighed 27.4 pounds. Of course, cotton fabric plus the dope finish probably weighed a bit more than Ceconite and modern paints do.
All this shows that your plane is in the right ballpark. I’ve seen ambulance models with empty weights of over 100# more than yours.
Jim
For oil cooler service I recommend R&E Oil Cooler Services in Prescott Valley, AZ. They have an outstanding national reputation, particularly among warbird and antique aircraft owners, and they are familiar with our honeycomb G&O coolers. They also clean, inspect and service vernatherms. The owner has a hangar near mine at DVT in Phoenix and has stopped in a few times on the rare occasions when we’re both there.
John,
OK, now I have more time for this and I see that no one else has chimed in yet. After thinking about it off and on all afternoon, I believe you may be right, there could be some sort of blockage to the oil cooler. If it was a more modern engine I’d suspect a faulty Vernatherm (thermostatic bypass valve), but our O-435’s don’t have one of those.
Earlier this evening I checked old emails from people with similar issues and found one from Fred Wright way back in 2012 quoting nearly identical oil temperature numbers – peaking at 105 and dropping to 87 degrees C. Incidentally, he was also breaking in fresh cylinders which always generates more heat than normal. In Fred’s case, it turned out to be a faulty oil cooler causing the problem. Of interest here is that some people in the northern climes bypass the oil cooler intentionally because the oil doesn’t heat up enough.
Anyway, to verify that the oil cooler isn’t doing its job is a simple matter of feeling the cooler and both the inlet and outlet lines shortly after flying, which should be long enough to raise the oil temperature to at least 80 degrees C., if not more. The lines and cooler body should all be about the same temp as the sump, although given the time required to uncowl the engine, the cooler and lines will lose heat more quickly than the sump. If you have one of those digital point-and-shoot infrared thermometers, that could be helpful. It might also avoid potentially blistered fingers. If the oil cooler and lines are significantly cooler than the sump, there’s probably a blockage somewhere.
One possibility that my Lycoming troubleshooting guide mentions is an air bubble trapped in the oil cooler that could be preventing positive flow. I’ve never experienced that with an airplane engine myself, but it’s a common issue I’ve come across with automotive cabin heater cores that don’t seem to get hot even though the rest of the engine is up to temp.
While you’re at it, obtain a long-stemmed high temp kitchen thermometer (metallic, not glass) such as a candy-making type or one that restaurants use for checking deep fryer oil. You can insert it in the dipstick hole and get a direct reading of oil temperature that you can compare to the gauge on your panel. The one I keep in my tool box cost about $20 and the stem is longer than the dipstick. It works nicely for verifying that a gauge isn’t lying to me and it’s more expedient than removing the gauge and bench testing it.
Other than the oil cooler and inlet/outlet lines getting plugged up with sludge, there’s nothing else I can think of than can cause a flow issue that won’t also affect oil pressure. My O-435 knowledge is a little hazy about this next point, but I think the supply side of the oil cooler is directly affected by the oil pressure relief valve. When it is dumping oil back into the sump to relieve excessive pressure, flow through the oil cooler is reduced. So, it occurs to me that maybe the relief valve in your engine isn’t seating properly due to a contaminant of some sort. If that is the case then lower pressure should be indicated by the gauge. This is one of the reasons I asked about oil pressure readings in my earlier quick reply.
That’s all I’ve got. Can anybody else to add to this or refute it? Sam…? Duncan?
Hi John,
There could be a several issues, including a lean-running engine, but I’m about to head out the door, so I’ll just ask two simple question s- what was the oil pressure doing, and have you checked the oil screens? I’ll get back to you later with some troubleshooting ideas unless Sam or someone else beats me to it.
Jim
Hi Craig,
The masthead piece is not ceramic, its stainless steel, I believe. If you look at some vintage photos where the light is just right, you can clearly see this to be the case. The ceramic piece in the antenna system was the insulator / fairlead at the top of the rudder.
Anyway, a few years ago (ok, probably a decade), a former L-5 owner named Jason Sharkey had access to a 3D scanning machine and had a batch made from an original. I imagine that all were probably sold and at least a few found their way onto some L-5 restorations. I was given one with a slight defect and have not used it yet but, alas, It’s buried in a box somewhere in my overstuffed hangar that is over 3,500 miles away from me. So, I can’t help at the moment and I won’t be back in Phoenix until next month, but it gives you a lead to follow up on.
I no longer have contact with Jason since I invited him out of the club due to his extremely mercenary price-no-object approach to scouring up highly sought after L-5 parts and RCA radio equipment and reselling at exorbitant prices, but I think you can locate him through the Indiana DeLorean Auto Club. If you’re a member of the LinkedIn network you can probably find him there too.
JG
Not necessarily correct, Chris. There were 8-bolt hubs, 6-bolt hubs, and an apparent hybrid (I have one) that appears to be an 8-bolt that was re-drilled to accommodate a 6-bolt propeller. The original hubs, starting with the first L-5’s were all 8-bolt. Then, sometime in 1943 (I’d have to look up the date), several Fairchild trainers with 8-Bolt Warner hubs suffered catastrophic propeller failures which were attributed to insufficient “meat” around the bolt holes. So, in what one might term a “knee jerk” reaction to avoid further fatalities and loss of aircraft, the USAAF decided to replace all the 20-spline 8-bolt hubs on all aircraft types using them with the 6-bolt design that had more wood around each bolt hole.
That, I suspect, led to a temporary shortage of 6-bolt hubs until Warner’s production facility could turn out a sufficient number to cover all of the airplanes affected, which included L-5’s. It is my belief that either Warner re-manufactured some hubs to make up the deficit, or a field mod was issued in the form of a Technical Order bulletin so repair depots could perform the work. Incidentally, no L-5’s are known to have suffered a failure of the 8-bolt props, but the hubs were changed anyway. One of the liaison squadron mechanics I used to know (now deceased) remembered seeing a great pile of perfectly good propellers being doused with gasoline and burned because they couldn’t use them anymore.
Somewhat ironically, the CAA (later FAA) never found reason to ban the 8-bolt hubs after WWII, so eventually many of the hubs removed by the military eventually ended up as surplus and found their way back into use on L-5’s. It is my guess that this is also why they seem to be more commonly found for sale than the 6-bolt version. Both types are getting hard to come by in good condition though, with corrosion being the main reason for rejection during annual inspections.
Hi Craig. While that isn’t really pertinent to the question asked by Bill, what you say is absolutely true and it is something that should be kept in mind in the context of restoring an L-5 to an historically authentic configuration. That stuff was heavy (!!!) and definitely reduced the performance of the planes. The more (ahem) “portly” owners like myself definitely need to consider that when contemplating a full-on restoration.
Your comment is no doubt in reference to the military Basic Weight Checklists that are shown for each model in the L-5 W&B handbook, so thanks for reminding me to upload a copy to the website for those owners who do not have one. Those checklists are very useful when reinstalling the original military equipment because they give the precise weight, arm and moment of each item which makes recalculating the CG and preparing a new equipment list a much easier task.
Hi Bill,
Great question. Actually, in the 20 years that I’ve been running the club no one has asked that question before. I’ll try to be thorough but concise with my answer and will use bullet points to help me stay organized.
* As you probably know, aircraft reference datum lines are arbitrarily chosen by the manufacturers. The primary datum reference for measuring all stations and the C.G. on the L-5 is at the tip of the crankshaft.
* In the side view illustration in AN01-50DB-5 you’ll notice that the datum line is shown 1.44″ from the end. That is because it is at the tip of the crankshaft, not at the tip of the prop nut which extends that little bit farther. Lycoming calculated the C.G. of the O-435 without a prop nuts installed and the Stinson engineers used that data for their subsequent design calculations.
* All of the arm lengths shown in the L-5 W&B charts and diagrams are measured from that primary datum. When weighing the aircraft and calculating the empty C.G. location, that is the point that should be used. Of course, leveling the aircraft fore-aft is important when weighing it since the arm of the tailwheel hub changes slightly with the tail raised to a level flight attitude.
* On the FAA’s Type Certificate Data Sheet the C.G. limits are given as +13.0 to +18.2 inches, which is in relation to THE LEADING EDGE OF THE WING, not the primary datum. Why they did this is unclear but I’d guess that it makes calculating C.G. as a percentage of the Mean Aerodynamic Chord a bit quicker. While we as pilots generally don’t do % MAC calculations for simple airplanes like the L-5, engineers do and the military does. If you look closely, the MAC percentages are given in the L-5 W&B handbook. In your 1950 version of the T.O. the range 20.5% to 32.0% of the MAC, although in earlier versions of the handbook the figures are slightly different.
* So, the answer to your question is that it’s probably wise to do both. Calculate the C.G. first by using the primary datum per the T.O. and then show conformance with the TCDS by simply subtracting 72 inches from the result — i.e. the distance from the primary datum to the wing leading edge.
* Additional observations…
1. The 1950 T.O. gives a C.G. range of 83.7 to 90.2 inches aft of the datum. Subtracting 72 inches yields 11.7 to 18.2 inches aft of the wing leading edge as opposed to the 13.0 to 18.2 inches on the TCDS. Oddly, an earlier version of the T.O. gives an allowable C.G. range of 83.3 to 90.9 inches , yielding 11.3 to 19.9 inches aft of the wing leading edge. This may account for the oversize trim tab the military fitted to some airplanes that allowed a wider C.G. range. It’s odd that none of the T.O. figures match the TCDS values.
2. For those interested in the % of MAC figures, you’ll find that for most conventional aircraft the center of the C.G. range is very close to 25% MAC, give or take 1%.
4. It is quite easy for an L-5 to exceed the forward CG limit on the “observer” model if a pilot weighs in excess of 225 pounds and the rear seat is empty, particularly if a controllable prop is installed. Ambulance models are more tail heavy and therefore more forgiving in that regard. Also, a center of gravity that is well behind the forward limit provides more positive steering control, especially in crosswinds.
I hope that covers it. Comments???
Jim Gray
First, be sure they’re L-5 tanks. The Stinson 108 fuel tanks look very similar and it’s easy to mistake the two. Many people have contacted me over the years thinking they had L-5 tanks when they were really for a Voyager. The 108 tanks are longer (20 gallons vs 18) and don’t have gauges on the inboard ends. As a point of reference, BAS advertises $500 per tank for clean, used 108 tanks, guaranteed to be in useable condition.
The problem with pricing L-5 tanks is they aren’t in high demand and shipping is expensive. When someone does need one, then it’s a different story. Shipping becomes more or less irrelevant. Since that doesn’t happen very often they should be priced low enough that someone would be inclined to buy them for a “rainy day”. I sat on a pair for ten years before they were needed.
Obviously, condition is important. If they have been cleaned and leak-tested, don’t have any patches, and the tops aren’t beat up they’re worth about what Sam quoted. If they include gauges, caps and vents, they’re worth a bit more. NOS in crates (a few of those have turned up in recent years), they’d be worth at least $1000 each. Cosmetically rough and un-tested, the cost of shipping makes them a hard sell, so it would be a matter of accepting whatever someone was willing to offer.
JG
p.s. To clarify on the O-290, I meant the superceded valve seat numbers, not valves. Also, on the O-435-1 the original valve seat part numbers were 60645 intake and 60337 exhaust. I wasn’t aware they might be sized differently from the -11 valve seats. That might have been the case with the early cylinder heads, p/n 65394 that were superceded by p/n 65756. These numbers should be cast into the heads, so for future reference I’m curious which heads are on your cylinders.
John,
Yes, there are different part numbers for the intake and exhaust valve seats. Apparently you haven’t eyeballed the valves yourself because they are noticeably different in size. From the -11 parts catalog the Exhaust Valve Seat is p/n 66527. The Intake Valve Seat is p/n 66528. Neither of these parts are currently made. This is the same valve seat set as used on the Lycoming O-290. On that engine, the exhaust valve was superceded by 72058 and I think the intake was superceded by the 72057, but I can’t seem to find my cross-reference data at the moment.
If memory serves, these later seats are also common with the Lyc , 320, 360, and 540 [at least on some versions], so you should be able to locate the parts easily enough. However, don’t take my word for it. Do your research and double-check the cross-references. When purchasing, also be aware that they were made in oversizes versions as well as standard. Gibson Aviation probably has them. Univair or Preferred Air Parts may have them too. Also be aware that when new seats are installed the valve guides should be replaced too, per instructions in the OH manual.
Good luck,
JG
Wes, I have digitized copies of the USAAF and Navy records for ALL 3,590 L-5’s delivered during WWII. Having looked at every single one of them multiple times I’m also very good at interpreting the acronyms and numerical codes on them. JG
Rocker shaft p/n 60401 and bushing 60398 are common parts used on O-235-C1, O-290-D, D2, D2C, O-360-A, IO-360-G, HIO-360-B O-540-A and IO-540-C/J). Many sources.
Valve spring retainer p/n 60009. Multiple engines, many sources. Aircraft Spruce has them.
Spruce also has O-435-A cylinder base gaskets and valve cover gaskets. Same set as used on O-435-C/C1 and O-290 and probably other engines.
Aircraft Specialties has the 66531 exhaust valves also used on the O-290-D.
The 66429 intake valve = 60037 = LW-11901 same as O-235 and O-290-D available from Superior Air Parts. There’s a set of 4 NOS on eBay for $298.
I sent you a private email about rings. Send me an email for a copy of the O-435 parts catalog if you don’t have one.
JG
