Saturday, December 1, 2012

Light weight starter

lightweight starter tag

                                 Never operate your starter in excess of 10 seconds per starting attempt.  Allow 20 seconds to allow starter to cool between attempts.  Repeat up to 5 more times (all Sky-Tec starters can handle at least a total of 60 seconds of combined cranking time per half hour - some far more - but don't test it!).  If engine fails to start, allow 30 minutes for starter to fully cool down before repeating (you might want to talk with a competent mechanic as to why your expensive aircraft engine didn't fire on 2-3 blades like the good ones always do).
          There are little to maintenance requirements for a Sky-Tec starter.  You may apply a very small amount of dry-silicone type lubricant or light LPS (1) to the drive pinion gear and/or shaft (Lycoming models) to minimize surface corrosion.  But typically the best maintenance for your Sky-Tec starter is regular use.  

                Never pressure wash the starter with water or any form of degreasing agent.  Simply wipe it clean to remove any surface contaminants.  

starting system


What is a kickback?  
            A kickback is a case in which a cylinder of your engine fires before the piston reaches TDC (top-dead-center) and the piston tries to go backward.  A single cylinder can produce as much as 25-50+ HP and is bound to win in setting the direction of rotation over a 2HP starter.  Kickbacks can be momentary:  Cylinders 1, 3 & 4 do the right thing and keep the prop going the right direction, but that #2 cylinder trying to go the wrong way sends a shocking impact to the whole engine and especially accessories - most namely, the STARTER. 
what causes kickbacks?
            The overall answer is, “The engine’s ignition system”.  That is to broad an answer to be really useful, so let’s narrow that down.  If a magneto has just been installed and was not static-timed correctly, a kickback may occur.  Other than that simple cause, different ignition systems can have different types of problems that are the root cause of the problem.  Let’s see which ones your aircraft may have: 
If you have a  “shower of sparks” starting system (also called “retard point mag”), go to #1, below.
If you have impulse couplers in both mags, go to #2, below.
If you have an impulse coupler in only one mag, go to #2, below. 
#1 Problems with “shower of sparks” starting systems.
             This type of system relies on a set of points on one of the magnetos that is set to fire at or after TDC and a vibrator system to generate multiple high-voltage sparks when this set of points is enabled.  The normal, advanced, set of points in both magnetos must be disabled during cranking or a kickback may occur. 
           A complex key switch for magneto selection and starting is used to perform this function.  When the key is turned to the START position, several things must happen at once:  the normal P-Leads of both magnetos are grounded to prevent the magnetos from firing too early, the P-Lead to the retarded points in one of the magnetos is un-grounded to enable firing at TDC, the “shower of sparks” vibrator is turned on and the starter relay is activated.  If any one of the following problems is present, a kickback may occur: 
           The key-switch is bad and one of the normal P-Leads remains ungrounded during cranking.  This allows the normal, advanced points to fire early and cause a kickback. 
   One of the P-Leads is broken or loose.  This allows the normal, advanced points to fire early and cause a kickback. 
One or both of the magnetos are defective. 
#2 Problems with impulse-coupler starting systems.
This type of system relies on a spring-loaded mechanism in one or both magnetos which, when turned slowly, will “snap” forward at the correct time and accelerate the armature in the magnetic field to produce a stronger spark.  At the same time, the firing is mechanically retarded to fire at TDC or after. 
                         If you have impulse couplers in BOTH magnetos, go to #3 below.  If you have an impulse coupler in only one (the left) magneto, one or more of the following problems can cause a kickback: 
You have a separate push-button for the starter and you are cranking with the magneto switch in the BOTH position.  This allows the magneto that does not have a coupler to fire early and cause a kickback.  You may get away with this starting procedure for years and hundreds of starts as the spark will be weak - but, one day, the mixture, temperature and fate will be just right an you will have a kickback. 
You have a separate push-button for the starter and you are cranking with the magneto switch in the LEFT position.  A defective switch or broken or loose P-Lead to the right magneto, allowing it to fire while cranking and cause a kickback. 
You have a key-start switch and the switch is defective or there is a broken or loose P-Lead to the right magneto, allowing it to fire while cranking and cause a kickback. 
The impulse coupler in the Left magneto is defective and fires early. 
#3 – impulse couplers in both magnetos. 
An impulse coupler in one of the magnetos is defective and fires early.
Troubleshooting the Ignition System 
                           Some simple tests can be made with an accurate mili-ohmmeter which will find many of the potential problems.  Measuring resistance between the aircraft frame (ground) and the P-Lead terminal on each magneto while trying to crank (with the battery disconnected, of course) should show low resistance to ground while attempting to crank the engine (for impulse coupled mags). 
Put a timing light on the magneto.  Is it firing before top dead center? 
                       Remember that, in the case of a key-start switch going bad, it may be intermittent.  Therefore, watching the meter while wiggling the key in the “crank” position may show the resistance to ground varying.  This indicates a switch problem.


Starter ERB-8012

 Starter  ERB-8012, Clockwise rotation, 24 Volt, 9 tooth - 10/12 Pitch Gear. The E-Drive starters do not have a core charge. These starters are sold as new outright without any core charges or returns. The E-Drive starters have a two year unlimited hours warranty period. Kelly Aerospace's new E-Drive starters offer distinct advantages over earlier Prestolite, Delco and even newer lightweight, permanent magnet starters. With the E-Drive starters, there is no mechanical Bendix, which makes them immune to kick-back damage. Fits all Lycoming engines, without modification. Also incorporates a solid-state solenoid control for greater reliability. The ERB8012 is an FAA/PMA approved replacement for MHB4015, MMU4001 and MMU6001.



Service Information Letter A 126

E-Drive Starter Features:

Immune to Kick-Back Damage 
»No Shear Pin costs here! Perfect spin
» Sweet spot engine starts. Does not drain your power like other starters.
Lightweight » Only 9.5 lbs.
No mechanical Bendix
Electromechanical solid-state solenoid
Powerful Permanent Magnet » High Torque Performance
Easy Installation » Lycoming engines
Tough » Tested under the most extreme environmental conditions
FAA/PMA approved
2 Year Unlimited Hours Warranty
Aviation Designed & Developed - No Automotive Aftermarket Parts Used!
Low Current Draw
12 volt or 24 volt
Superior Duty Cycle
TBO Starter - Capable of providing Maintenance Free service to your engine's TBO... and beyond.

Solid-State Solenoid Control
The Printed Circuit Board (PCB) solenoid controller uses the latest in Surface Mount Technology (SMT) components. Each control is environmentally hardened and tested under the most extreme conditions. The field serviceable unit eliminates mechanical contacts for improved reliability and longer life. Monitoring the health status of the engine, starter, battery, and operational duty cycle will soon become a reality through enhancements to our proprietary solenoid control system.

E-Drive Starter vs. Sky-tec 149-NL

E-Drive Lycoming aircraft starter
Cranking Speed (rpm) 
is the speed at which your starter rotates the engine's crankshaft during a start. You may think that a higher cranking speed would be better but this is not always the case. Your starter is part of the engine's starting system which also includes the fuel and ignition systems. These systems have been designed to provide good starting characteristics for a particular starting speed range. For most engines this speed is between 120 and 180 rpm. Cranking your engine faster than 200 rpm may disengage the magneto impulse couplings thereby advancing the ignition timing which will result in poor engine starting and can even induce kickbacks! A typical 6 cylinder Lycoming engine requires 50-60 ft*lbs of torque to start. For this load condition, consider the following comparison (see chart, point B for Edrive and point D for Sky-Tec).

Sky-Tec - Spins the engine too fast
295/305 rpm at 50 ft*lbs of torque.
E-Drive - Ideal cranking, well below limit
145/155 rpm at 50 ft*lbs of torque.
Current Draw 
directly affects the amount of heat that builds up in your starter when cranking your engine. The more current your starter pulls, the more heat that is generated in the starter. Increased heat reduces cranking performance, shortens the overall life of your starter and drains your battery. The rate of temperature increase also decreases the duty cycle of the starter which means fewer starts before the starter reaches its temperature limit. Current draw also affects other components in the aircraft starter electrical system. Contactors, terminals, and cables are all adversely affected by high current draw. Current draw is particularly important to pilots who have the battery located in the rear of the aircraft. The cable between the battery and the starter acts as a resistor which causes a voltage drop over its length. As current increases so does this voltage drop. The resulting electrical power lost to heat over the length of the cable is not available for use by the starter. Higher current draw results in greater voltage drop and less power to the starter. For cranking a typical Lycoming 6-cylinder engine with a 24-volt system and assuming a 50 ft*lb torque load the following comparison should be considered (see chart).

Sky-Tec - Pulls about 2-1/2 times as much current, shortening starter life
165/175 amps
E-Drive - More than Double the number of starts and duty cycle of Sky-Tec!
60/70 amps
Current Draw also determines the number of starts you can get from your battery. For a given charge condition, your battery is capable of delivering a given number of starts and that number is directly related to the amount of current your starter draws while cranking. A starter drawing twice the current will only give you half the number of starts before battery depletion.

Duty Cycle
is important as it reflects how well the starter can tolerate repeated starting attempts and over-cranking abuse. Warranty data from starter manufacturers indicates that the principle cause of in-service starter motor failures is over-cranking abuse. A starter with a duty cycle twice that of another will be able to deliver twice the number of starts within a given window of time without overheating. This is an important performance indicator when considering a starter as it will have a direct impact on starter longevity.

The operational limitations for the E-Drive are 10-seconds of engagement time followed by 20-seconds of rest for 20 consecutive starts! No other starter can match that kind of performance!

The Hartzell starters have undergone rigorous durability & laboratory tests including operating at temperatures ranging from -45 to 180°F shock tests, sinusoidal vibration sweeps, load cycling, normal starting, abusive starting, starting with induced kick-backs, and other environmental/operational extremes. The new starter lines from Hartzell Engine Technologies are capable of providing maintenance free service to your engine's TBO... and beyond.