Ch 30 - Airframe Contimination And Deformation Flashcards

1
Q

Contaminations

A
Frost
Snow
Heavy Snow
Rime Ice
Clear Ice 
Heavy Rain
Dirt
Oil
Other Fluids
Sand
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2
Q

Frost

A

Contamination, if on the ground, just brush it off or de-ice depending on size of AC

Caused by moisture in the air, attaching to a freezing airframe only below a certain speed

When descending, it usually accumulates under the wings as the cool fuel rests on the bottom of the wing tanks

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3
Q

Snow and Heavy Snow

A

Knock it off if light AC, De-ice the wings and the fuselage area

Increases the mass and stalling speeds

Can damage airframe if falling off in large chunks of damaging the control surfaces (hinge points)

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4
Q

Rime Ice

A

Crystalline structure, easy to see because there is lots of air trapped in the freezing process

Not as heavy as clear ice due tom the air

Effects; Aerodynamics, forms at slower speed on the leading edges

Fixed by either de-icing boots (pneumatic) or thermal mat

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5
Q

Clear Ice

A

Far more dangerous as it is much heavier and changes the shape of the aerofoil drastically

Can restrict control surfaces and is difficult to spot

Occurs on speeds less than 250kts (both clear and rime) and at temperatures <5C

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6
Q

Aircrafts Prone to Icing

A

Usually slow and operate in the mid altitude ranges

Turbo props, propeller aircraft

Turbojets only really a problem for TO and for Approach/Landing

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7
Q

Stalling Due to Contamination

A

Stalling angle decreases with frost and severely with ice

Stalling speed increases

Tail plane stall possible due to icing of the tail

Ice on tail can lead to a CG moving aft slightly (if prone) to prepare for the stall

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8
Q

Contamination hazard for TO

A

More drag induced by the contaminant which leads to a decrease in excess thrust

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9
Q

Icing on Leading Edges

A

More icing on sharper leading edges - tail or Fin

Tail poses a real problem, especially if it is an all moving tail plane as you would lose elevator authority

Fin is not so much of a problem unless engine failure etc

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10
Q

Icing Impacts with Flaps deployed

A

Increased downwash leads to an increased AoA on the tail.

If the tail is iced, the stalling AoA is lower and due to the separation bubble, is likely to stall which could be a real problem during finals. Even just with small elevator inputs, you risk stalling the tail

If there is a possibility of tail icing, test authority with flaps deployed high up in the approach

Descend with anti-icing equipment on if possible especially if going into cold most air

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11
Q

Before TO

A

De-Ice first, removing the ice (anti-icing equipment will help with this)

Auto pilot will not help, will just trim out the effects until it is too late so engage at a higher alt on the climb and disengage at a higher alt on the approach so that you have feel and can see if anything is up.

Q-Feel isn’t as effective with icing as you potentially cant feel the change

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12
Q

De-Icing Truck

A

Uses hot water and anti-icing fluids to remove the ice on aircraft. There is then a time limit to which you can then take off before you have to be re de-iced

At a busy airfield, this will be just before the threshold

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13
Q

Heavy Rain

A

Increases the mass of the AC which increases the skin friction drag and leads to an increased Stalling Speed

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14
Q

Degradation

A

Paint over time will wear and be dirty so every ~3 years (depending on use and areas operating in) will need to respray.

You can only usually respray an aircraft 3 times before you then need to totally strip it to bare metal and completely redo the paint due to the increasing weight every time.

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15
Q

Deformation

A

Damage of the airframe increases the drag as well as decreasing the structural integrity of the AC

Repaired with patches if not to major

Baggage handlers are most likely to damage AC

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