Aviation Engines Part 27

Short circuit anywhere. }

CARBURETION SYSTEM FAULTS SUMMARIZED

_Motor Starts Hard or Will Not Start_

No Gasoline in Tank.

No Gasoline in Carburetor Float Chamber.

Tank Shut-Off Closed.

Clogged Filter Screen.

Fuel Supply Pipe Clogged.

Gasoline Level Too Low.

Gasoline Level Too High (Flooding).

Bent or Stuck Float Lever.

Loose or Defective Inlet Manifold.

Not Enough Gasoline at Jet.

Cylinders Flooded with Gas.

Fuel Soaked Cork Float (Causes Flooding).

Water in Carburetor Spray Nozzle.

Dirt in Float Chamber.

Gas Mixture Too Lean.

Carburetor Frozen (Winter Only).

_Motor Stops In Flight_

Gasoline Shut-Off Valve Jarred Closed.

Gasoline Supply Pipe Clogged.

No Gasoline in Tank.

Spray Nozzle Stopped Up.

Water in Spray Nozzle.

Particles of Carbon Between Spark-Plug Points.

Magneto Short Circuited by Ground in Wire.

Air Lock in Gasoline Pipe.

Broken Air Line or Leaky Tank (Pressure Feed System Only).

Fuel Supply Pipe Partially Clogged.

Air Vent in Tank Filler Cap Stopped Up (Gravity and Vacuum Feed System).

Float Needle Valve Stuck.

Water or Dirt in Spray Nozzle.

Mixture Adjusting Needle Jarred Loose (Rotary Motors Only).

_Motor Races, Will Not Throttle Down_

Air Leak in Inlet Piping.

Air Leak Through Inlet Valve Guides.

Control Rods Broken.

Defective Induction Pipe Joints.

Leaky Carburetor f.l.a.n.g.e Packing.

Throttle Not Closing.

Poor Slow Speed Adjustment (Zenith Carburetor).

_Motor Misfires_

Carburetor Float Chamber Getting Dry.

Water or Dirt in Gasoline.

Poor Gasoline Adjustment (Rotary Motors).

Not Enough Gasoline in Float Chamber.

Too Much Gasoline, Carburetor Flooding.

Incorrect Jet or Choke (Zenith Carburetor).

Broken Cylinder Head Packing Between Cylinders.

_Noisy Operation_

Popping or Blowing Back in Carburetor.

Incorrectly Timed Inlet Valves.

Inlet Valve Not Seating.

Defective Inlet Valve Spring.

Dirt Under Inlet Valve Seat.

Not Enough Gasoline (Open Needle Valve).

m.u.f.fler or Manifold Explosions.

Mixture Not Exploding Regularly.

Exhaust Valve Sticking.

Dirt Under Exhaust Valve Seat.

CHAPTER XI

Tools for Adjusting and Erecting--Forms of Wrenches--Use and Care of Files--Split Pin Removal and Installation--Complete Chisel Set--Drilling Machines--Drills, Reamers, Taps and Dies-- Measuring Tools--Micrometer Calipers and Their Use--Typical Tool Outfits--Special Hall-Scott Tools--Overhauling Airplane Engines --Taking Engine Down--Defects in Cylinders--Carbon Deposits, Cause and Prevention--Use of Carbon Sc.r.a.pers--Burning Out Carbon with Oxygen--Repairing Scored Cylinders--Valve Removal and Inspection--Reseating and Truing Valves--Valve Grinding Processes--Depreciation in Valve Operating System--Piston Troubles--Piston Ring Manipulation--Fitting Piston Rings-- Wrist-Pin Wear--Inspection and Refitting of Engine Bearings-- Sc.r.a.ping Bra.s.ses to Fit--Fitting Connecting Rods--Testing for Bearing Parallelism--Cam-Shafts and Timing Gears--Precautions in Rea.s.sembling Parts.

TOOLS FOR ADJUSTING AND ERECTING

[Ill.u.s.tration: Fig. 163.--Practical Hand Tools Useful in Dismantling and Repairing Airplane Engines.]

A very complete outfit of small tools, some of which are furnished as part of the tool equipment of various engines are shown in group at Fig.

163. This group includes all of the tools necessary to complete a very practical kit and it is not unusual for the mechanic who is continually dismantling and erecting engines to possess even a larger a.s.sortment than indicated. The small bench vise provided is a useful auxiliary that can be clamped to any convenient bench or table or even fuselage longeron in an emergency and should have jaws at least three inches wide and capable of opening four or five inches. It is especially useful in that it will save trips to the bench vises, as it has adequate capacity to handle practically any of the small parts that need to be worked on when making repairs. A blow torch, tinner's snips and soldering copper are very useful in sheet metal work and in making any repairs requiring the use of solder. The torch can be used in any operation requiring a source of heat. The large box wrench shown under the vise is used for removing large special nuts and sometimes has one end of the proper size to fit the valve chamber cap. The piston ring removers are easily made from thin strips of sheet metal securely brazed or soldered to a light wire handle. These are used in sets of three for removing and applying piston rings in a manner to be indicated. The uses of the wrenches, screw drivers, and pliers shown are known to all and the variety outlined should be sufficient for all ordinary work of restoration. The wrench equipment is very complete, including a set of open end S-wrenches to fit all standard bolts, a spanner wrench, socket or box wrenches for bolts that are inaccessible with the ordinary type, adjustable end wrenches, a thin monkey wrench of medium size, a bicycle wrench for handling small nuts and bolts, a Stillson wrench for pipe and a large adjustable monkey wrench for the stubborn fastenings of large size.

Four different types of pliers are shown, one being a parallel jaw type with size cutting attachment, while the other ill.u.s.trated near it is a combination parallel jaw type adapted for use on round work as well as in handling flat stock. The most popular form of pliers is the combination pattern shown beneath the socket wrench set. This is made of substantial drop forgings having a hinged joint that can be set so that a very wide opening at the jaws is possible. These can be used on round work and for wire cutting as well as for handling flat work. Round nose pliers are very useful also.

A very complete set of files, including square, half round, mill, flat b.a.s.t.a.r.d, three-cornered and rat tail are also necessary. A hacksaw frame and a number of saws, some with fine teeth for tubing and others with coa.r.s.er teeth for bar or solid stock will be found almost indispensable.

A complete punch and chisel set should be provided, samples of which are shown in the group while the complete outfit is outlined in another ill.u.s.tration. A number of different forms and sizes of chisels are necessary, as one type is not suitable for all cla.s.ses of work. The adjustable end wrenches can be used in many places where a monkey wrench cannot be fitted and where it will be difficult to use a wrench having a fixed opening. The Stillson pipe wrench is useful in turning studs, round rods, and pipes that cannot be turned by any other means. A complete shop kit must necessarily include various sizes for Stillson and monkey wrenches, as no one size can be expected to handle the wide range of work the engine repairman must cope with. Three sizes of each form of wrench can be used, one, a 6 inch, is as small as is needed while, a 12 inch tool will handle almost any piece of pipe or nut used in engine construction.

Three or four sizes of hammers should be provided, according to individual requirement, these being small riveting, medium and heavyweight machinist's hammers. A very practical tool of this nature for the repair shop can be used as a hammer, screw driver or pry iron.