Angle of Incidence Checking

The angle of incidence of a wing is the angle formed by intersection of the wing chord line and the horizontal axis of the aircraft.

Checking and adjusting angle of incidence

1. Leveled the fuselage.
2. use incidence Board.

Note: Same in dihedral checking.

Washin and Washout

Washin and washout are employed to give the wings on each side of an aircraft a slightly different amount of lift in order to aid in couteracting the effect of engine and propeller torque.

• Washin is an increase in the angle of incidence of the wing from the root to the tip. An angle of incidence 2 degrees at the root and angle of incidence of 3 degrees ate the outer end, it has a washin 1 degrees
• Washout is a decreasing angle of incidence from the root to the tip of a wings.washout is also used to provide improved stall characteristics.

Fixed-Surface Alignment and Effect of rigging on Flight

Symmetry Check

A misaligned condition can seriously affect the flying qualities of the aircraft.

Misalignment may not apparent by casual observation and may be founded only be alignment checks using instruments.

Note: Alignment check is normally make after any major structural repair or after the airplane has been subjected to severe conditions.

A symmetry check is used to verify this alignment and is determined by first leveling the aircraft and then measuring the disrances from reference points on the aircraft central axis to reference point on the adjustable components.

Note: If all measurements are within the tolerances given in the maintenance manual, the aircraft is in correct alignment,Vice versa.

The vertical symmetry of an aircraft can be checked by the use of measuring tape to check the distance between the tip of the vertical stabilizer and the horizontal stabilizer.

Some Technicians lay out the reference point on the floor of the hangar by used of plumb bob, so they can make the measurement on the floor.

Effect of rigging on flight

The Purpose of rigging an aircraft is to obtain the most efficient flight characteristic possible.

A properly rigged and trimmed airplane will fly straight and level, "hands off" at its normal cruise speed.If it disturbed by the air, it will correct itself and resume straight and level flight.

Note:If the aircraft is out of rig, meaning that the component are not properly aligned.

Aircraft Rigging And Leveling the aircraft

Aircraft Rigging

Aircraft rigging involves two principle types of operations.

1. The aircraft structure must be rigged for correct alignment of all fixed components,The structures are aligned at the time of positioned in the assembly jig and then start to assembly.
2. Type of rigging is the alignment of control surfaces and the controls that move the surfaces.These operation require the adjustment of cable length, cable tension, push-pull rod, bell cranks, cable drums, and various other parts.

Note: Angular deflection of control surfaces must be measured with protractors or other measuring 

devices.

Leveling the aircraft

When rigging the aircraft, It may necessary to establish the aircraft in a level attitude(ฺBoth longitudinal and lateral levels) prior to checking and adjusting wings and control surfaces.once the aircraft is level longitudinally and laterally, the component can be rigged.

One method used on many light aircraft is to set up a spirit level on a longitudinal structure to establish the longitudinal level position and another level across specific structural members to establish the lateral level position.

Screw can be placed into two nut plates on the side of the fuselage, a spirit level placed on the extended screw for leveling the aircraft.

Some aircraft make use of a plumb bob and a target to establish the aircraft level attitude on both axes.

If the aircraft is not level, it can be leveled by the use of supports under the aircraft, such as jacks or tail stands. The inflation of tires and struts can be adjusted, as can the fuel loads in wings and fuselage.

Note: Care must be taken not to place a support jack at a structural weak area such as on skin panel between bulkhead,If the air pressure is reduced in tire or struts to establish the aircraft level attitude or if fuel is tranfered for this purpose, the aircraft must be properly servicing be fore it is returned to operations.

Repair of Cracks in Noncritical Area

Engine Cowling and Baffles are subjected to a great deal of vibration and often crack.If the crack is not stopped, it will grow until the component is seriously damaged.

• When a crack is discovered, drill a small hole with a #40 or #30 drill slightly beyond the end of the visible crack. This hole distributes the stresses at the end of the crack so they will be less than the tensile strength of the metal. Install a patch over the crack to prevent vibration from causing further damage to weakened component.

Repair of Sheet Metal Structure

Basic Requirement: 

1. The material being repaired must restore to its original form.
2. The material being repaired must as light weight as possible.
3. The material being repaired not distort the aerodynamic shape of the aircraft.
4. The material being repaired not change the weight of a component in such a way that it cause flutter or vibration.
5. The material being repaired must be approved by the FAA.

Classification of Damage Damage

can be classified into three categories: 

1. Negligible Damage.

• Is that does not affect the airworthiness of the aircraft. 

2. Repairable Damage.

• Damage that can be repaired by the replacement of skins and repairs that are described in the structural repair manual. 

3. Damage that requires replacement of the component.

• Damage that involves extensive corrosion, or part that are damaged beyond the limits specified in the structural repair manual. Next : Is how to repair the damaged parts.

Aircraft Batteries

There are two types of aircraft batteries which common use today

1. Lead-Acid
2. Nickel-Cadmium

Both of these devices use positive and negative plates in an electrolyte.

Note, Aircraft batteries do not supply electricity for the normal operation of electrical system in flight(These are function of generator and alternator). The purpose of aircraft batteries is to operate the starter and to supply power for intermittent electrical loads whose current demands exceed the output of the Generator

Next article will talk about lead-acid battery. click link below

Lead-Acid Batteries

Lead-Acid Batteries - Construction of Lead-Acid Battery

In this content we explain lead-acid in to the 6 section as the following

1. Construction - Now you're here
2. Chemistry
3. Battery Rating
4. Dry Charged Batteries
5. Battery Testing and Charging
6. Battery Installation and Servicing

1.Construction of lead-acid battery.

1,1 Grid

Grid is framework for the active element in lead-acid battery formed by cast of alloy of lead and antimony.The open space of grids are filled with the active ingredient.

1.2 Negative Plates

Negative plates are grids which  have their opening filled with a dull grey.mass spongy of porous lead.It have an expander  mixed into it to prevent the losing of lead from the surface of plates.

1.3 Positive Plates

Positive Plates are grids which have their opening filled with a chocolate brown, a compound of lead peroxide with highly porous 

1.4 Separators

Separator made from micro porous rubber. having vertical rib s next to the positive plate.This rib allows a greater volume of acid to be held in contact with positive plates and improve the efficiency of the cell and to retard the loss of  lead peroxide after continued cycling.

1.5 Cell Element 

Batteries always have one more negative .plate than the positive plates to protect the more active positive plates and prevent warpage by exposing both sides equally.All cell elements are connected with a connector strap welded onto each plate.

1.6 Container 

Container of batteries are made by molding and can be classified into 2 types as

1. Vented - without a separated box
2. Unvented - connected with a rubber hose to an air scoop outside the airplane and go through the sump jar where they are neutralized.

1.7 Cell Connectors

Older batteries's are connected with a strap welded to the post  up through the cell cover.

newer batteries are connected with a through-partition cell connector. This type provides a shorter path for the high current flow.

1.8 Cell Covers and Vents

A lead weight actuated  valve allows the filler plug to vent when upright,but seals when tipped

1.9 Battery Terminals(Post)

Usually located on the top or the side,Side mounted terminal are usually fitted with a quick disconnect connector.

Note:The polarity,POS and NEG is normally molded into the cover in raised letters.

1.10 Electrolyte

This electrolyte are Sulfuric acid and water in a ratio of 65:35 (water:acid) by weight .This produces a specific gravity of about 1.265 at 80 degrees F.

Note: Electrolyte causes changes in positive and negative plates and in electrolyte itself.

End..

Next will be the Chemistry of lead-acid batteries. Click.