VH to Raaus

[RFguy]

Type 24 aircraft cannot be modified in any way without a manufacturers Letter Of Approval and manufacturers seem very reluctant to provide them.

if its rego is changed to 24-experimental it can

Edited September 20, 2020 by RFguy

[skippydiesel]

Type 24 aircraft cannot be modified in any way without a manufacturers Letter Of Approval and manufacturers seem very reluctant to provide them.

No offence but I think this is in the category of a sweeping statement - not all manufactures are so rigid.

[Downunder]

Type 24 aircraft cannot be modified in any way without a manufacturers Letter Of Approval and manufacturers seem very reluctant to provide them.

Lot's of "24" have faults that can be improved.

My take on why they are reluctant to provide letters of approval is because they don't want to admit liability or fault for the original setup.....for EVERY aircraft manufactured the same.

Which makes it hard to legitimately improve a poor design .......... when the mfg's response is to stick their head in the sand and pretend it doesn't exist.

One common issue I've seen on Rotax powered aircraft is WAY underspec battery to starter cable......probably to save weight.

Even high end euro designs having cable below Rotax recommended minimum spec.

Constant poor starting ends up with a failed "sprag clutch" which then costs thousands to replace.......

[onetrack]

Re the starter cable, you can use Aluminium cable of a much larger cross-section with no weight penalty - for a substantially increased current flow. Aluminium is the 4th most conductive metal behind Silver, Copper and Gold in that order.

 

I have an Isuzu truck that used Aluminium starter cable from the factory in 1989. However, I did have to replace it with copper, because the Aluminium cable started to fracture at the starter connection, after 25 yrs of engine movement.

 

I suspect the cost of Copper is what makes manufacturers skimp on cable size - or go to Aluminium cable. After all, Copper is a precious metal, and still used for currency.

[RFguy]

I would NOT recommend Aluminium because of the fatigue behaviour in a high vibration environment !

No way. If it flexes or deforms beyond any value it will fail ! just how long it depends.

The weight of the copper is not much, you are not using much of it !!!

It is going to be like having an extra glass of beer in your stomach. That's all the weight difference is going to be.

Use a high strand count copper cable and correct swage or clamp connections.

 

-Glen

Edited September 20, 2020 by RFguy

[skippydiesel]

Lot's of "24" have faults that can be improved.

My take on why they are reluctant to provide letters of approval is because they don't want to admit liability or fault for the original setup.....for EVERY aircraft manufactured the same.

Which makes it hard to legitimately improve a poor design .......... when the mfg's response is to stick their head in the sand and pretend it doesn't exist.

One common issue I've seen on Rotax powered aircraft is WAY underspec battery to starter cable......probably to save weight.

Even high end euro designs having cable below Rotax recommended minimum spec.

Constant poor starting ends up with a failed "sprag clutch" which then costs thousands to replace.......

 

In my view you ae reading the "rules" far to rigidly - I can not believe that replacement of some thing as mundane as a battery cable should be a problem. The factory specifications are in the category of a minimum required ie you must replace with the same or verifiably higher spec.

 

The rules must allow for changes in technology or obsolesce, you can replace your battery with a higher performing one, as long as its physical dimensions fit within the cradle and there is no change to your weight & balance.

 

In my, admittedly limited experience, the manufacturer was cooperative when presented with a reasoned argument and a solution/recommendation - I would not bother them with a battery cable replacement.

[Mewp]

Skippy I stand corrected. No offence taken.