OUTER WING SURFACES AND TAIL SECTION

The pilot should inspect for any signs of deterioration,

distortion, and loose or missing rivets or screws,

especially in the area where the outer skin attaches to

the airplane structure. [Figure 2-6] The pilot should

look along the wing spar rivet line-from the wingtip

to the fuselage-for skin distortion. Any ripples and/or

waves may be an indication of internal damage

or failure.

Loose or sheared aluminum rivets may be identified by

the presence of black oxide which forms rapidly when

the rivet works free in its hole. Pressure applied to the

skin adjacent to the rivet head will help verify the

loosened condition of the rivet.

When examining the outer wing surface, it should be

remembered that any damage, distortion, or

malformation of the wing leading edge renders the

airplane unairworthy. Serious dents in the leading

edge, and disrepair of items such as stall strips, and

deicer boots can cause the airplane to be

aerodynamically unsound. Also, special care should

be taken when examining the wingtips. Airplane

wingtips are usually fiberglass. They are easily

damaged and subject to cracking. The pilot should

look at stop drilled cracks for evidence of crack

progression, which can, under some circumstances,

lead to in-flight failure of the wingtip.

The pilot should remember that fuel stains anywhere

on the wing warrant further investigation-no matter

how old the stains appear to be. Fuel stains are a sign

of probable fuel leakage. On airplanes equipped with

integral fuel tanks, evidence of fuel leakage can be

found along rivet lines along the underside of

the wing.

FUEL AND OIL

Particular attention should be paid to the fuel quantity,

type and grade, and quality. [Figure 2-7] Many fuel

tanks are very sensitive to airplane attitude when

attempting to fuel for maximum capacity. Nosewheel

strut extension, both high as well as low, can

significantly alter the attitude, and therefore the fuel

capacity. The airplane attitude can also be affected

laterally by a ramp that slopes, leaving one wing

slightly higher than another. Always confirm the fuel

quantity indicated on the fuel gauges by visually

inspecting the level of each tank.

The type, grade, and color of fuel are critical to safe

operation. The only widely available aviation gasoline

(AVGAS) grade in the United States is low-lead

100-octane, or 100LL. AVGAS is dyed for easy

recognition of its grade and has a familiar gasoline

scent. Jet-A, or jet fuel, is a kerosene-based fuel for

turbine powered airplanes. It has disastrous

consequences when inadvertently introduced into

reciprocating airplane engines. The piston engine

operating on jet fuel may start, run, and power the

airplane, but will fail because the engine has been

destroyed from detonation.

Jet fuel has a distinctive kerosene scent and is oily to

the touch when rubbed between fingers. Jet fuel is

clear or straw colored, although it may appear dyed

when mixed in a tank containing AVGAS. When a few

drops of AVGAS are placed upon white paper, they

evaporate quickly and leave just a trace of dye. In

comparison, jet fuel is slower to evaporate and leaves

an oily smudge. Jet fuel refueling trucks and

dispensing equipment are marked with JET-A placards

in white letters on a black background. Prudent pilots

will supervise fueling to ensure that the correct tanks

are filled with the right quantity, type, and grade of

fuel. The pilot should always ensure that the fuel caps

have been securely replaced following each fueling.

Engines certificated for grades 80/87 or 91/96 AVGAS

will run satisfactorily on 100LL. The reverse is not

true. Fuel of a lower grade/octane, if found, should

never be substituted for a required higher grade.

Detonation will severely damage the engine in a very

short period of time.

Automotive gasoline is sometimes used as a substitute

fuel in certain airplanes. Its use is acceptable only

when the particular airplane has been issued a

supplemental type certificate (STC) to both the

airframe and engine allowing its use.

Checking for water and other sediment contamination

is a key preflight element. Water tends to accumulate

in fuel tanks from condensation, particularly in

partially filled tanks. Because water is heavier than

fuel, it tends to collect in the low points of the fuel

system. Water can also be introduced into the fuel

system from deteriorated gas cap seals exposed to rain,

or from the supplier's storage tanks and delivery

vehicles. Sediment contamination can arise from dust

and dirt entering the tanks during refueling, or from

deteriorating rubber fuel tanks or tank sealant.

The best preventive measure is to minimize the

opportunity for water to condense in the tanks. If

possible, the fuel tanks should be completely filled

with the proper grade of fuel after each flight, or at

least filled after the last flight of the day. The more fuel

there is in the tanks, the less opportunity for

condensation to occur. Keeping fuel tanks filled is also

the best way to slow the aging of rubber fuel tanks and

tank sealant.

Sufficient fuel should be drained from the fuel strainer

quick drain and from each fuel tank sump to check for

fuel grade/color, water, dirt, and smell. If water is

present, it will usually be in bead-like droplets,

different in color (usually clear, sometimes muddy), in

the bottom of the sample. In extreme cases, do not

overlook the possibility that the entire sample,

particularly a small sample, is water. If water is found

in the first fuel sample, further samples should be taken

until no water appears. Significant and/or consistent

water or sediment contamination are grounds for

further investigation by qualified maintenance

personnel. Each fuel tank sump should be drained

during preflight and after refueling.

The fuel tank vent is an important part of a preflight

inspection. Unless outside air is able to enter the tank

as fuel is drawn out, the eventual result will be fuel

gauge malfunction and/or fuel starvation. During the

preflight inspection, the pilot should be alert for any signs of

vent tubing damage,

as well as vent blockage.

A functional check of the fuel vent system can be done

simply by opening the fuel cap. If there is a rush of air

when the fuel tank cap is cracked, there could be a

serious problem with the vent system.

The oil level should be checked during each preflight

and rechecked with each refueling. Reciprocating

airplane engines can be expected to consume a small

amount of oil during normal operation. If the

consumption grows or suddenly changes, qualified

maintenance personnel should investigate. If line

service personnel add oil to the engine, the pilot should

ensure that the oil cap has been securely replaced.

LANDING GEAR,TIRES, AND BRAKES

Tires should be inspected for proper inflation, as well

as cuts, bruises, wear, bulges, imbedded foreign object,

and deterioration. As a general rule, tires with cord

showing, and those with cracked sidewalls are

considered unairworthy.

Brakes and brake systems should be checked for rust

and corrosion, loose nuts/bolts, alignment, brake pad

wear/cracks, signs of hydraulic fluid leakage, and

hydraulic line security/abrasion.

An examination of the nose gear should include the

shimmy damper, which is painted white, and the torque

link, which is painted red, for proper servicing and

general condition. All landing gear shock struts should

also be checked for proper inflation.

ENGINE AND PROPELLER

The pilot should make note of the condition of the

engine cowling. [Figure 2-8] If the cowling rivet heads

reveal aluminum oxide residue, and chipped paint

surrounding and radiating away from the cowling rivet

heads, it is a sign that the rivets have been rotating until

the holes have been elongated. If allowed to continue,

the cowling may eventually separate from the airplane

in flight.

Certain engine/propeller combinations require

installation of a prop spinner for proper engine

cooling. In these cases, the engine should not be

operated unless the spinner is present and properly

installed. The pilot should inspect the propeller

spinner and spinner mounting plate for security of

attachment, any signs of chafing of propeller blades,

and defects such as cracking. A cracked spinner is

unairworthy.

The propeller should be checked for nicks, cracks,

pitting, corrosion, and security. The propeller hub

should be checked for oil leaks, and the alternator/

generator drive belt should be checked for proper

tension and signs of wear.

When inspecting inside the cowling, the pilot should

look for signs of fuel dye which may indicate a fuel

leak. The pilot should check for oil leaks, deterioration

of oil lines, and to make certain that the oil cap, filter,

oil cooler and drain plug are secure. The exhaust

system should be checked for white stains caused by

exhaust leaks at the cylinder head or cracks in the

stacks. The heat muffs should also be checked for

general condition and signs of cracks or leaks.

The air filter should be checked for condition and

secure fit, as well as hydraulic lines for deterioration

and/or leaks. The pilot should also check for loose or

foreign objects inside the cowling such as bird nests,

shop rags, and/or tools. All visible wires and lines

should be checked for security and condition. And

lastly, when the cowling is closed, the cowling

fasteners should be checked for security.