Hydraulic Fluid

From Wikipedia:

Aircraft hydraulic systems

The use of hydraulic systems in aircraft almost certainly began with braking systems.^{[citation needed]} As aircraft performance increased in mid-20th century, the amount of force required to operate mechanical flight controls became excessive, and hydraulic systems were introduced to reduce pilot effort. The hydraulic actuators are controlled by valves; these in turn are operated directly by input from the aircrew (hydro-mechanical) or by computers obeying control laws (fly by wire). See flight controls.

Hydraulic power is used for other purposes. It can be stored in accumulators to start an auxiliary power unit (APU) for self-starting the aircraft’s main engines. Many aircraft equipped with the M61 family of cannon use hydraulic power to drive the gun system, permitting reliable high rates of fire.

The hydraulic power itself comes from pumps driven by the engines directly, or by electrically driven pumps. In modern commercial aircraft these are electrically driven pumps; should all the engines fail in flight the pilot will deploy a propeller-driven electric generator which is concealed under the fuselage.^[3] This provides electrical power for the hydraulic pumps and control sysytems as power is no longer available from the engines. In that system and others electric pumps can provide both redundancy and the means of operating hydraulic systems without the engines operating, which can be very useful during maintenance.

[edit] Specifications

Aircraft hydraulic fluids fall under various specifications:

Common petroleum-based:

• Mil-H-5606: Mineral base, flammable, fairly low flashpoint, usable from −65 °F (−54 °C) to 275 °F (135 °C), red color
• Mil-H-83282: Synthetic hydrocarbon base, higher flashpoint, self-extinguishing, backward compatible to -5606, red color
• Mil-H-87257: A development of -83282 fluid to improve its low temperature viscosity.

Phosphate-ester based:

• BMS 3-11: Skydrol 500B-4, Skydrol LD-4, Skydrol 5 and Exxon HyJetIV-A plus – Typically light purple, not compatible with petroleum-based fluids, will not support combustion.

What this means

There are two types to worry about.

• Skydrol which is synthetic and use plastic seals.
• OM15/H515/H5606, these are mineral based and use rubber seals.

Do not mix them up!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Actuators

Have a look at https://services.train.army.mil/soldierPortal/atia/adlsc/view/public/9590-1/fm/5-499/chap4.htm to find out a bit more about actuators, this site seems reasonably clear.

Eindecker from Omaka Museum NZ

 

This picture from the Omaka Website is of a Fokker Eidecker. Very few aircraft in WWI were monoplanes, why was this?

I would also say that Omaka is the best museum in New Zealand and should be a compulsory visit for Te Papa staff to see how it should be done.

Flight Controls

What are the primary and secondary flying controls?

Define primary and secondary flying controls? Chocolate fish if you can. 🙂

Comments and questions please.

Work so Far

A Moving Experience

Most people are now underway, very much like the above; for some it is rather slow, I would expect that US 21834 would be finished by Friday, I would like to see it from those who have not finished yet by Monday.

Two Questions

There are two questions you need to answer.

1. Why do we use the Phoenetic Alphabet?

2. Why do we use the 24hour clock in aviation?

Post your answers here.

The Phoenetic Alphabet

The Phonetic Alphabet,

Can you tell me without thinging what the Phonetic pronunciation of POA is, or ZK HGD. It should be like times tables, if you can not name all the letters instantly then, you need to do more work.

If you know of any easy ways of learning the alphabet post them here I know alot of other people will be interested.

Remember Questions and comments are very welcome.

Introduction

Hi all,

If you are not really interested in the Catlins Area School L2 and L3 aviation course than you are probably in the wrong place, but what the hell have a look anyway.

Welcome if you are here for the aviation course, I hope this blog is useful to you. There will be links to work and sites that will help. there will also be comments from me and I hope you.

I expect this post to be up a long time before the course starts but there is nothing like being prepared.