Astar 350 & 355 Electrical Troubleshooting Tool

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If you’ve ever had an electrical problem on an Astar with the old style fuses you are not alone. One of the biggest problems of troubleshooting your problem is that you will need several fuses of the right amperage and volts to find the problem. This means carrying around a lot of fuses which is not very practical. So I will show you how to build a simple tool for troubleshooting these types of problems.





Here is what you will need:
(Substitute or improvise as you wish)

- one 10 amp breaker
- one 5 amp breaker
- one 2 amp breaker
- a RadioShack project box ( or build box of your choice)
- some wire and connectors ( you may select the gauge you want)
- one old fuse large style
- one old fuse small style
- one large fuse cap
- one small fuse cap
- connector of your choice


STEP 1: Take your radio shack box and fit the three breakers in the box.




STEP 2: Wire them in parallel as shown in the picture above. Drill a hole in the side of
the box to allow the two wires out and attach a connector of your choice.


STEP 3: Drill a small hole in each end of your fuses (be very careful the fuses break
easily). Also drill a hole in each of your fuse caps.

STEP 4: Now take and slide a wire through the cap and through the fuse. Solder the end
of the wire to the end of the fuse.

STEP 5: Next take and slide another wire through the cap beside the first, this wire is
soldered to the other end of the fuse.

STEP 6: Now attach a connector to each of these fuse/fuse cap setups.


Here is the tool in use in a 10 amp circuit.



Now you can easily insert either of these fuses into a circuit you are having problems with, choose the amperage of that circuit by pushing in the appropriate circuit breaker and connect the box and the fuse/fuse cap together at the connector. If there is a problem, example wire grounding out, the breaker will pop. Use this tool till you find the problem and fix it. Then insert the correct fuse and you are done. No wasted fuses. Hope this helps.

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EC120B Hydraulic Troubleshooting

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The following are some steps to take when you have no hydraulics and the hydraulic light is on.

SYMPTOM:
PILOTE REPORTS NO HYDRAULIC ASSIST TO FLIGHT CONTROLS AND HYDRAULIC LIGHT IS ON.


TROUBLESHOOTING:
1. FIRST DETURMINE IF THE FAILURE IS DUE TO ELECTRICAL OR MECHANICAL PROBLEM.

2. PREFORM GROUND RUN, LOOK AT SIGHT GLASS ON HYD PACK, HYD FLUID SHOULD BE CIRCULATING.
a. IF FLUID IS CIRCULATING: ELECTRICAL PROBLEM.
b. IF FLUID IS NOT CIRCULATING: MECHANICAL PROBLEM.

ELECTRICAL: Ref: WDM 29-11-00-001 & 29-31-00-001

“ELECTRIC VALVE”

1.CHECK B6, 3 AMP CIRCUIT BREAKER, ON CARGO CIRCUIT BREAKER PANEL.

2. CHECK FOR 28 VOLTS AT PIN 2, WITH HYD SWITCH IN THE ON POSITION. AT THE ELECTRICAL VALVE LOCATED ON THE HYD PACK.

3. CHECK GROUND FROM ELE VALVE PIN 1.

NOTE: ELECTRIC VALVE CAN BE SWAPPED WITH SERVO ELE. VALVE FOR TROUBLESHOOTING “SAME PART NUMBER”

“PRESSURE WARNING”

1. CHECK FOR 28 VOLTS AT PIN 1, ON HYD PRESSURE SWITCH.

2. CHECK GROUND FROM PRESS SWITCH PIN 3.



MECHANICAL:

1. CHECK SPLINE DRIVE BETWEEN HYD PACK AND MGB.

2.BROKEN ROLL PIN ON MUFF COUPLING.

3. WORN SPLINES ON HYD PACK OR MGB.

4. CHECK ROTATION OF HYD DRIVE SHAFT IN MGB.

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TEN TOOLS EVERY HELICOPTER MECHANIC SHOULD HAVE

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1. Ratcheting screwdriver- you can get these almost everywhere from canadian tire to the dollar store. so you will have to find one you like and that works best for you. They come with different handle shapes and changeable shafts. The one that seems to be the choice of most engineer is the old style snap on ratcheting screwdriver. Made with a hard plastic handle it won't be affected by grease or oil. It is very durable and you can store extra bits in the handle. The downside is its snap-on and it’s not cheap. The one thing for sure is you will get your money back in use.

2. Ratchet with Socket set 1/4 inch 12 point- These sockets will be your most used. Depending on what type of helicopter you work on they may be metric or standard. You can also get these anywhere. They range in price from 10 dollars to 200 dollars depending on the manufacture. These like the ratcheting screwdriver will be well used.


3. Torque wrench- There will be many times when a torque wrench will be required for the job you are doing. The most common one you will use is the 1/4" drive 20 inch pounds to 200 inch pounds. There are a few other sizes you will require but its best to have at least this one for everyday use.


4. Magnify glass- A magnify glass will come in very handy when inspecting many components. What type is up to you? Make sure it is at least 10 times power. Good place to buy a quality one is from a geology shop.

5. Duckbill pliers- These guys will come in handy for almost everything like installing cotter pins, lock wiring and grabbing on to hard to reach items. You will use these almost daily.

6. Side cutters- Same as the duckbill pliers they will come in handy for many of your daily activities so buy a decent pair that will hold up to much usage.

7. Flashlight- Sounds kind of obvious, but a good flashlight will go along way. There are many types to choose from. Everything from halogen to LED. Just make sure you get one that is bright. Another thing to consider is one that also has black lights in it. This will allow you to see oil leaks better. The oil will glow under black light.

8. Multimeter- This tool will come in handy for any electrical problem you will encounter. There are many different types and models. Fluke makes a really nice product but are very expensive. What ever brand you decide to purchase make sure it has the functions you will need.


9. Hammer and Brass Punch- These guys will come in handy for removing bolts, installing rivets and many other things. Get at least a 8oz. hammer.
10. Knipex- This tool has been around for a short time. They come in many different sizes. Small being 6 inch, medium being 10 inch and large being 12 inch. The only place I've seen these for sale is on a snap-on truck. They cost around 100 dollars, but are worth it. You will find many uses for these pliers.


Well there are ten items you should have in your toolbox to make your life easier. There are many other items that I have not mentioned because they are not used as often as these.

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EUROCOPTER AS 350 AND AS355 BALANCING TIPS

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Here are some tips to think about when having trouble balancing an Astar. These tips can also be used when balancing the twinstar with a few exceptions.

1. Check the yellow pitch link length. After initial rigging it should not be moved for any reason. Its measurement should be approximately 372mm bolt to bolt center line on thick sleeve installations. On thin sleeve installations (older style) it should be 378.5mm from bolt to bolt center line (On a twinstar the length is different). If incorrect length it will affect autorotation, overall ride and NR governor speed.

2. Check to make sure the blades were put on in the correct locations. Blue should be over the rotating scissors. When BLUE is placed forward over the nose of the aircraft RED is on the left and YELLOW on the right.

3. Check that the blade trim tabs are in the correct locations using a trim tab bending tool. You will find the correct tab degrees on the blade log card. Both inboard tabs are initially set to zero. Do not put back to zero unless you are starting over at nominal. These are the tabs that you are allowed to move for balancing purposes.

4. Check the rigging by turning hydraulics off while running on the ground. If the track picture changes, the main rotor controls need rigging with the appropriate rigging tool.

5. Check if you have weights on the blue blade. There should be zero. Only in rare occasions will you have weights on this blade usually because of something not correctly installed on the main rotor head. ex. frequency adapter upside down, interrupter in wrong location.

6. Make sure your interrupter is under red blade.

7. Check all main rotor head bolts for correct torque.

8. Check that windshield screws are tight.





9. Check your starflex ball joints for play (.016") max. If there is excessive play you may experience ground resonance.






10. Check that the frequency adapters have their arrows pointing up. Also check frequency adapters for wear. If you get a sudden increase in vibration and ground resonance take a very close look at them.

11. AVA lower bearing may be worn. This will cause an imbalance not track problems.

12. A starting point for weights on the blades is BLUE = 0, RED = 4, Yellow = 6.

13. Make sure to mount Lateral accelerometer on Mast. Mount vertical accelerometer at first bolt hole forward of where chin bubble meets the floor.

14. Track on ground moving pitch links looking at tip targets. Track in hover moving pitch links looking at tip targets. Adjust red and blue to yellow. DO NOT ADJUST YELLOW.

15. Adjust track at 60 knots - use pitch links. Adjust track at cruise speed or 110 knots Plot the ips from the vertical accelerometer on the tab chart. Adjust the required tab. always try to tab up. Remember up is minus on the chart. It is sometimes better to tab one blade at a time. (you can look at the tip targets as a reference but a perfect track does not mean a smooth ride)

16. Get the vertical to .2 ips. If you go lower than this the three per rev will increase.

17. If you have a balanced helicopter with a low ips reading and you still feel roughness in flight it may be caused by one of the following. - short shaft out of balance - pitch link rod end bearings - loose windshield screws - frequency adapter ball joints loose - trim tabs on the same blade in plus and some in minus - servo rod end bearings loose - Fwd tail rotor drive shaft hanger bearing mount cracked - Starter generator vibrating - engine vibration - Tail rotor out of balance.

I hope this information will help anyone having trouble with balancing an Astar. Please check your appropriate maintenance manuals before performing any work on your aircraft.

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INSPECTION OF BELL THOMAS COUPLINGS

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Thomas couplings are located on bell helicopters 206, 206L on the tail rotor driveshaft. The amount of couplings will vary depending on style of driveshaft (one piece driveshaft, or segmented driveshaft). They allow for misalignment of the shaft and flexing during flight.

One thing I find overlooked at the 100 hour inspections are the Thomas couplings. It is not a requirement to pull them apart and clean them unless they are showing separation of 0.003” between the discs. It seems if you wait until there is 0.003” separation usually the discs are heavily pitted and you will need to replace them. I recommend you pull them apart and clean them at the first sign of separation. This will prevent pitting and give you maximum life of the coupling. Below are a few pictures showing some things you should look for when inspecting and how to clean the Thomas couplings.

When inspecting the coupling you should look for separation of the discs and cracks. Any separation the discs should be removed and cleaned. Any cracks you should replace the coupling.

You should also look for couplings that have been assembled wrong. The discs should alternate. Below you will see a coupling assembled wrong

The hardware holding the discs together can differ in stack up of washers due to driveshaft installation tolerances. Make sure you install the same hardware back in the same location. Also make sure that washers that are beside the coupling are beveled on the one side that is against the coupling.

CLEANING THE COUPLING

To clean the coupling, first remove it from the aircraft. Make sure you do not mix the discs up or change their alignment. The coupling must go back on exactly how it came off. One way of doing this is by using a bolt or lock wire through one of the holes when the coupling is removed. This allows you to separate the discs for cleaning without losing there orientation.

Now that you have the coupling off and a bolt in one hole to prevent mixing the discs up, clean the corrosion off with soap and a piece of scotchbrite. After you have done all 3 holes move the bolt/lockwire to one of the other holes and clean the last one.

After this you should check for pitting where you have removed the corrosion. Check the manual for the max allowed. If there is no pitting or it is within tolerance, spray the coupling down with WD 40 or T9. Then wipe it off. You can now reassemble the coupling on the aircraft.



Once the coupling is reinstalled you will notice there is no gap between the plates.



After you have installed it and retorqued the coupling you should inspect it to make sure you have put the washers on correctly and that the discs are in the correct position.



By cleaning these couplings sooner than when they get 0.003” separation you should be able to prevent any pitting on the plates and maximize there life.

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