Navajo obscure questions

Louis · Post by **Louis** » Wed May 18, 2005 11:04 am

Hi,

I would like to know if anyone of you had some tricky questions that might come up on a PPC or flight test for the Piper Navajo, much like the King Air thread there was a while ago...

Thanks in advance,

Louis

fougapilot · Post by **fougapilot** » Wed May 18, 2005 11:18 am

Ahhh, Louis is getting ready for his initial IFR...

What is the relation between the electrical system and the landing gear?

D

Mostly Harmless · Post by **Mostly Harmless** » Wed May 18, 2005 11:56 am

What is the one item in the electrical system that can fail and cause a complete electrical failure?

fougapilot · Post by **fougapilot** » Wed May 18, 2005 12:11 pm

Mostly Harmless wrote:What is the one item in the electrical system that can fail and cause a complete electrical failure?

That would depend on what year Navajo you are flying... (if my memory serves me right)

SkyKing · Post by **SkyKing** » Wed May 18, 2005 12:54 pm

How about some answers too!

fougapilot · Post by **fougapilot** » Wed May 18, 2005 3:20 pm

Ahh, but they are for Louis to answer...

Louis · Post by **Louis** » Wed May 18, 2005 7:08 pm

fougapilot wrote:
Mostly Harmless wrote:What is the one item in the electrical system that can fail and cause a complete electrical failure?
That would depend on what year Navajo you are flying... (if my memory serves me right)

Thanks everyone, keep 'em coming.

If it's of any help, the two Navajos I am interested in were built in 1980 and 1981 respectively.

Goodbye,

Louis

flyinhigh · Post by **flyinhigh** » Wed May 18, 2005 8:13 pm

when I did my ride a year ago, I found it to actually be very straight forward they didn't ask any kinda questions to trick me up, and if there was something that your not sure of, just know where to find it

Ron Graham · Post by **Ron Graham** » Wed May 18, 2005 9:46 pm

This is actually a good question. Skywings in Red Deer had a complete electrical failure on a ppc ride a week and a half ago. Dead battery caused it all (both main and aux.) systems. Thier machine has mechanical hydralic pumps on each engine which would make operation of the gear independet from the electrical system. Alot of other Piper aircraft use an electric over hydralic system which can cause a certain amount of concern while your in the seat trying to figure out why the gear won't drop. The only thing that the electrics do for the gear on thier machine is pull up the inner gear doors. This is my take on the topic as explained to me by the owner of the aircraft.

fougapilot · Post by **fougapilot** » Thu May 19, 2005 6:59 am

RG gets the 20points.

On most Navajos (this is the way they were built) the only relation between the electrical system and the landing gear is the gear doors. When you remove electrical power, at the end of a flight, you can hear a distinct "clunk". This is the gear door relay de-energizing, when it is de-enrgized it allows pressure (if it were applied) to lower the doors. During the normal gear cycle, it will de-energize to open the doors, wait until the three green lights are illuminated and the re-energize to close the doors. Should you have a complete electrical failure the relay won't be able to re-energize therefore the gear dors will remain open.

Next time you fly your Nav do this for fun before engine start;

With all electrics off, open the manual landing gear extention pand and pump just a few strokes. The gear doors will automatically open. Then turn the Batt Master on, you will hear the "clunck" pump again and they will close.

Best of luck on your initial Louis.

Dan

COCO THE MONKEY · Post by **COCO THE MONKEY** » Thu May 19, 2005 8:26 am

Regarding the experiment with moving the pump handle with the master off - mostly right but the gear doors will not close when you turn the master back on. They are not electric (must be hydraulic?) When the engines are started you will hear them clunk close. This is probably what fougapilot meant....

fougapilot · Post by **fougapilot** » Thu May 19, 2005 12:37 pm

Tbone,

It has been a long time since I flew a Nav, but if my memory serves me right, you could build the required hydraulic pressure with the hand pump.

Would have to try to see. 2500hrs in those things and can't remember... must be old age

Doc · Post by **Doc** » Thu May 19, 2005 4:23 pm

How many Navajo pilots does it take to open a beer?

hazatude · Post by **hazatude** » Thu May 19, 2005 4:57 pm

Doc wrote:How many Navajo pilots does it take to open a beer?

How many does it take?

Louis · Post by **Louis** » Thu May 19, 2005 5:12 pm

Finally had the time to research the gear question a bit.

The main gear door actuators are hydraulic, there is however a door solenoid valve that is controlled by the up and down limit microswitches. In case of an electrical failure, a spring moves this valve moves to the open position, allowing the doors to open once the selector is in the down position. However, should the gear be raised afterwards, the inboard doors will remain open as the solenoid valve can't move. One question: does Vle apply?

Note: The fact this valve remains in the open position is also what allows us to open said doors (with the emergency extension handle) prior to doing the walk-around.

Also, I would really like to know more about the "one item in the electrical system that can fail and cause a complete electrical failure"

I don't really expect so called "trick" questions on the multi or IFR rides, but what we're doing here gets me to search and probably get a better understanding of my systems than if I were just reading the books and poring over diagrams. I'll assume it might do the same for others. I've asked around the school for some questions and I thought Avcanada would be another good place.

Thanks everyone, and once again, keep em' coming,

Louis

P.S. There is also the gear indicator system that could be considered as part of the gear-electrical systems relation.

Spinner · Post by **Spinner** » Thu May 19, 2005 7:19 pm

Let me try one louis:

if you have an electrical failure and try to bring the gear up will it go?

PA31 Driver · Post by **PA31 Driver** » Thu May 19, 2005 7:55 pm

I'm still waiting for the answer to the beer question ?

fougapilot · Post by **fougapilot** » Thu May 19, 2005 8:34 pm

PA31 driver wrote:I'm still waiting for the answer to the beer question ?

Last time I went out for a few with the Navajo guys I flew with, I say a couple of drivers open way tooo many of them

If my memory serves me right, it involved beers, sunglasses and a double flip from the top of the house boat....

never did find the Raybands...

JigglyBus · Post by **JigglyBus** » Thu May 19, 2005 9:37 pm

Real question is how many Navajo drivers does it take to purchase a beer.

hazatude · Post by **hazatude** » Fri May 20, 2005 3:32 am

PA31 driver wrote:I'm still waiting for the answer to the beer question ?

Answer: None...

LINECREW BETTER HAVE THE DAMN BEER OPEN AND IN A BUCKET OF ICE

flyinhigh · Post by **flyinhigh** » Fri May 20, 2005 3:52 am

Hey Louis,
I will say that it is nice to see that all speculation on here is making you read and research on your own, it is nice to see that your not just asking questions here and trying to find the answer the easy way.

that said, I am sure that your HO does not have a P2 audio advisory on it, but if it does than heres one, if you are on final, have 3 green handle neutral and the system tells you to check gear, is your gear actually safe?

Louis · Post by **Louis** » Fri May 20, 2005 6:07 am

Spinner wrote:Let me try one louis:

if you have an electrical failure and try to bring the gear up will it go?

Not unless something is wrong with the anti-retraction solenoid latch in the gear selector mechanism, which defaults to "prevent retraction" unless the microswitches sends a signal to the effect that the main gear oleo is fully extended.

Flyinhigh, what is a P2 audio advisory? (I gather you're not talking about the gear warning horn in the throttle mechanism)

Goodbye,

Louis

COCO THE MONKEY · Post by **COCO THE MONKEY** » Fri May 20, 2005 10:12 am

Fougapilot - you are right (with engine shut down) that after pumping the handle dropping the doors,when you turn the master back on and THEN manually pump the handle, the gear doors will close. I was being a stickler, I guess and was just clarifying that it takes more than turning the master back on.

I used to give the exams for the PA31 and the question of whether the gear would come up with the master off was posed and the answer was yes, as I recall, but the gear doors would remain open. Raising the gear handle activates hydraulic valve(s) independent of electrics.

Another: What is the significance of the nose landing light operating normally but no green light on the nosewheel? A bit obscure maybe.

answer: the nose landing light uses a microswitch (look for it on a walkaround) which if closed should be as good an indication of nose down and locked as the down switch indicating that the latter is probably faulty. Check with your AMEs to assure they agree. Ours did.

Yet another: Loss of engine oil pressure causes the turbo wastegate to ... move toward open or close?

answer: open - this causes a reduction in manifold pressure which should cause you to glance at the oil press. as this could be a warning of impending engine failure (caused by the prop feathering as oil press. is required to hold the prop out of feather). Or just another turbo failure.

Spinner · Post by **Spinner** » Fri May 20, 2005 10:21 am

Tbone

the gear will not come up with the master off because as Louis says you cannot get the handle past the anti retraction solenoid pin.
(although I have seen a few pins that were bent like someone tried)

True or false instrument air is cut off to the copilots instruments during deice boot operations

COCO THE MONKEY · Post by **COCO THE MONKEY** » Fri May 20, 2005 2:34 pm

Spinner - I been out of this for a few years and should have the books at hand before I wrote that one. What you said makes sense. OOps!