PA31 Engine Failure Drill

[flying-spike]

This may or may not be related to the tragic accident at Canley Vale but who amongst us, endorsed on PA31, would physically select the gear up as part of the engine failure drill if it is already up?

[Capt Fathom]

I see the price of bread has risen again.....! :bored:

[Toruk Macto]

I would like to know also if there is someone with a tech back ground. The prop governor is controlled by oil pressure and fly weights I believe. If you had a complete loss of oil quantity, very quickly , would you be able to still feather the prop? If you lose pressure would the prop locks work to keep the prop fine / course.

[flying-spike]

The question is necessarily cryptic because I am trying to gauge the level of systems knowledge amongst those endorsed on the type and because a lack of knowledge of that particular system can be a huge gotcha on final with an engine failed.

[The Green Goblin]

Been a while since I flew the PA31 (3 years now) however you should check the hydraulic pumps on each engine every flight. Start the left engine first, once she has started pull the gear selector down. On shutdown you would shut the left engine down first then select gear down again to check the right pump.

If you had a left engine failure and you had not had the opportunity to check the right pump, then it's operation could be questioned and you would be wondering if there was enough residual pressure in the system to lower the gear. If however there was not, there is always a manual gear extension available to you. It could be too late however when you decide to lower it to find out you have no pressure and require a manual extension, particularly if you have left it late in the approach sequence due to the marginal performance that is characteristic of a PA31 on one donk.

The gear doors might also open when you select gear up. This is a huge drag penalty if you can't get them closed even with two engines running.

Are you implying the gear doors could have been open on PGW after the gear was selected up on the engine failure drills and was a contributing factor in the loss of performance?

[waren9]

Flying Spike

There are better, more effective ways if imparting your valuable knowledge than this one.

Your approach comes across as rather wankerish.

If you've got something to share it then do so. Otherwise start a poll.

[flying-spike]

Ok, I will come out with it now. I don't think it is in the manual, but if you select the gear up (with it already up) if there is sufficient pressure from the surviving pump the handle will just reset from the up to the up neutral position. If the handle doesn't reset or is very slow you know you may not be able to extend the gear with the remaining pump and be faced with a manual extention and will have to plan your descent and approach accordingly. I hope that helps somebody

[flying-spike]

If there is ever a ****** it would be the one who comes to soon. Read my considered response

[waren9]

With that in mind then, as per your first post
1. How is selecting up in an engine failure drill a "gotcha" in a PA-31 when it is already up?
2. How could it possibly have anything to do with the Canley Vale accident?

[flying-spike]

Consider this: You are on final, haven't checked the gear will come down with the surviving pump, then when you do select the gear down it just unlocks and dangles. Large amounts of drag, pulling you towards Vmca and not enough time to manually extend the gear. I did say it may or may not be a factor in this accident but if helps prevent an accident I will gladly be called "wankerish" by the likes of you. After all I just had to explain that to you.

[The Green Goblin]

Personally I'd be more worried about the gear doors not closing after takeoff when an engine failed and having a dicky pump on the live engine.

[waren9]

Well done on the change of tack.

Imparting knowledge with the use of poorly worded and obscure questioning is generally considered a poor instructional technique.

Is this widely useful for most light twins or is it PA31 specific?

[The Green Goblin]

is this widely useful for most light twins or is it PA31 specific?

PA31 specific.

A PA31 has two hydraulic pumps operating a common system powered by each engine. Either is capable of operating the system on their own at a reduced rate. Most light twins have an electrically driven pump.

When you select gear up or down in the PA31 after the cycle is complete the gear handle will spring back to the neutral position. Sometimes it will be very slow if the engine is at idle or the pump is dicky. If you check it and it does not spring back to the neutral position the pump(s) are faulty.

Quite common on takeoff is for the gear doors to not close properly and you will have a red gear position light. Instead of selecting the gear down again and then up, you just need to lift the handle from neutral to up and it should solve the problem then spring back to neutral when the system is pressurized again.

Thinking about this further I don't think the gear doors could open if you selected the gear up in your EFATO drill. It could dissipate pressure in the system for an extension if the operating engines pump was faulty however as I previously mentioned.

[waren9]

Thanks GG, and Flying Spike for that matter.

That was a quick reply GG, no kiwis to bash lately?:E

[The Green Goblin]

That was a quick reply GG, no kiwis to bash lately?

Nah, winters come, the grass is green and all the Kiwis are out in their fields tending to their flocks :}

[flying-spike]

Thanks GG for the explanation, thats at least two of us that know about the system. I was going to expand on it but you beat me to it and did a better job than I would have done.

P.S. I wonder if Waren 9 knows of his namesake in QF? If he did he may well be an expert on "wankerishness"

[flying-spike]

I only ever had it happen once and that was on take-off in a Dove. PA31, I am not sure but I am sure it has something to do with with those roller thingies on the flapp runners I used to check underneath every pre-flight.
Piper service letter 959 also explains the mod to fix problems with th 20:1 drive as well. Might be worth a look

http://www.airdisaster.com/reports/ntsb/AAR82-11.pdf

is also a good read

[The Green Goblin]

The good 'ole assymetric flap extension in the PA31 :ugh:

Many I flew had the runners jammed so the flaps could not extend past 30 degrees, you used to be able to get it pretty slow at 40 degrees that's for sure!

I used to count when I selected flap on the Navajos, 1000, 2000, 3000. That would give me 10 degrees on downwind. Count the same again for 20 degrees and let them run down on their own for 30 (or 40) degrees. I used to count to 5 for the cowl flaps too. That would give you a 5 knot reduction in airspeed and was good to slow down if you were a little too quick on your profile (in warm weather) I'd leave them closed until exiting the runway if it were cold.

As much as they are a bucket, I do miss them occasionally but I cry for a Baron and a 404!

[flying-spike]

My technique was to close both until at a safe height then open on the live engine. They create more drag than you might think.

[Grogmonster]

Well I have been waiting for a while and no one has mentioned that there are different PA31's as in I understand some PA31-310's only have one hydraulic pump. Any comments!

groggy

[The Green Goblin]

Even the early model Navajos that I flew had two. I have never heard of one having only one.

You may be thinking of the mighty Aztec?

[iogrsw]

early model Aerostars only had one engine driven hydraulic pump

[717tech]

I check the pumps every flight in the way that has been explained. What the manual doesn’t tell you is what is an acceptable time and what isn’t.... discussed with the engineer and was told that anymore than 11 seconds= dicky pump.....

[43Inches]

EFATO and Cowl Flaps
About 50 to 100 fpm I think, noticeable during normal operations. However the engine will very quickly build up temps with the cowl flaps closed, if you do close the live engine flaps monitor the temps. I would leave the live engine flaps open, best to keep your only friend as happy as possible. Definately close the dead engine ones when time permits.


I understand some PA31-310's only have one hydraulic pump


Aztec problem not the PA31 series, all the Navajos and Chieftains had the same problematic gear system, with some minor differences in cabling vs pushrods. There is no way to release the uplocks if your hydraulic fluid is lost, no matter how many pumps you have (engine, hand or ram air) the gear remains firmly up and locked. The up and down locks are very fickle and require good pre-flight and maintenance checking to prevent problems.


Assymetric Flap


Have had two occurances of this both during pre-flight checks in later models which prevent flap actuation if a split is detected. Both were due to the screw jack threading. In the earlier models (pre 1975 i think) the assy flap protection only worked if the flap assymetry started from flap zero or retracting from full flap, if occuring from an intermediate point there was no protection and almost full flap assymetry could occur. In any model extention of flap in small increments in flight will help early detection before it becomes a major control problem.

[pc12togo]

Hi all

I have some 8000hrs of great flying in the PA31-350 and not once did the old girl give me a scare. There were 5 PA31,s in the fleet and were about the same with build dates from 74 through 82.

I admit that it has been a few years since i flew one but do remember most of the operational requirments of it.

TORUK

The prop governor is controlled by oil pressure and fly weights. If you had a complete loss of oil quantity, very quickly , the prop will feather without you doing anything due to the lack of oil pressure. The only way the prop locks will work to keep the prop fine is if the engine gets below 800 rpm. If that happens then the prop will not feather. I have seen this happen to one of the aircraft after a fuel fire and the Pilot put the aircraft into a dive to put it out after shutting of the fire wall shut off valve, he did not feather the prop. When he pulled out of the dive to gain some height back, he then tried to feather to prop but it was stuck in fine. The only way to get it to feather would be to restart the engine to get it above 800rpm.

The out come of this was that with a shut down engine, and a prop not feathered he could not hold height and the landing on a rough road took out the undercarrage.

717tech

As for the gear and hyd pump check you are correct and i did this on every flight.

There has been a lot of talk about the lack of performance on one engine.
I have had a number of shutdowns over that 8000 hrs and not once have i been not able to hold height on one, on hot days and heavy loads.One of the shutdowns was on climb when a seal and a vac pump let go and pumped all the oil out of the right engine, which started the prop into feather before i started to pull the prop lever. I was able to turn back some 70 nm out and climb to 7000ft as i had to cross 50nm water, and was was able to hold that alt all the way back.

43Inches

Your comments as i see it are correct.

As for assymetric flap, i cant remember having a problem, but the aircraft were well looked after

[glekichi]

Thanks GG for the explanation, thats at least two of us that know about the system

Oh for f-sake spike do you actually think you're special for knowing the undercarriage system of a PA31? Are you implying that someone is giving endorsements without teaching it?

Start the left engine first

Hey goblin I been agreeing with you way too much lately. Finally something to prove that you are backwards afterall!

[PPRuNeUser0182]

I have some 8000hrs of great flying in the PA31-350 and not once did the old girl give me a scare.

+

I have had a number of shutdowns

=

:eek::E

[The Green Goblin]

Quote:
Start the left engine first
Hey goblin I been agreeing with you way too much lately. Finally something to prove that you are backwards afterall!

Don't worry mate, just to throw a spanner in the works I used to start the right engine first on the return leg or second sector and reverse the procedure I described in my first post for even running times :}

Of course now on the turbines it's always the right engine first :ok:

[jib]

Toruk Macto
Re the loss of oil pressure scenario, you are correct that it should feather, I can speak from experience. The other think I can add from experience is that the single engine performance of the PA-31 (admittedly the Chieftain at about MTOW) is woeful. I also ran out of sky, fortunately with something larger and softer to hit.

[bushy]

43 inches
Tell me about the cabling and/or pushrods in the PA31 undercarriage. As I remember them there was a hydraulic ram for each wheel.
The handpump for the hydraulic system had a saatandpipe which held enough fluid to lower the gear, and this fluid would still be there after a leak in the main system.

[The Green Goblin]

From memory when the gear was up and the uplocks held the gear the hydraulic pressure released and the gear would be held by the uplocks and not the pressure in combination with the uplocks.

When you hand pump the ram is pressurized to extend but I can't remember what disengages the uplock. There is a standpipe in the system to prevent complete loss of fluid like any system however I can't for the life of me remember about the uplock???

[pc12togo]

Information Charles

The shut downs did not give me a scare.

Start the right engine first so you could here the starter was in good order. Then the left as you could hear that starter as well.

[43Inches]

Tell me about the cabling and/or pushrods in the PA31 undercarriage. As I remember them there was a hydraulic ram for each wheel.
The handpump for the hydraulic system had a saatandpipe which held enough fluid to lower the gear, and this fluid would still be there after a leak in the main system.


From very distant memory the uplocks were connected to the actuator mechanism via pushrod in early models and cables in the later model.

Have seen a few instances of the actuator breaking and releasing fluid then there is nothing to release the uplock (on that leg) and only gravity fall if it does unlock. I suppose its more actuator failure than a straight out fluid loss issue. It would have been better for the system to have an uplock release mechanism independant of the hydrualics and gravity fall.

The down locks were a bit touchy about lubrication and roller freedom. Tested the downlocks by lifting them slightly during pre-flight to ensure freedom.

[Delta_7]

Flying-spike.

When on the ground with both engines off, do the gear doors go up or is it down by using the hand pump? Just delving into your type knowledge.

[dreamjob]

Delta_7: Gear doors go down when you pump on the ground.

A lot of what people are saying here can't be found in the POH. It's good to hear what other drivers have to say. :)

[flying-spike]

I suppose I should have added " out of the respondents on here" not trying to sound smug but also not wanting to state what whould be the bleeding obvious. And yes (I know grammatically incorrect), I am insinuating that there are dodgy endorsements. I have personally seen a C402 endorsement done in one lap of the Phillip Island circuit and checked a newly endorsed pilot (by somebody else) who told me the PA31 had and electrically actuated undercarriage!

[flying-spike]

Mate I would only be guessing, it has been 17 years since I flew one and haven't preflighted one for that long. I still have my endorsing notes though

[Capt Fathom]

checked a newly endorsed pilot (by somebody else) who told me the PA31 had and electrically actuated undercarriage!

Hmmm....

Maybe newly endorsed pilot should have read the POH!

[Sillo777]

On another note, colmill do an STC to remove the inner flipper doors.

This would take some of the electrical switching for the HYD system out of the equation.

From memory after gear retraction when the inner doors are closing and don't close the micro switch fully, the system then gives you a red in transit light and the inner doors drop and are left flapping free.

This STC should stop this happening ??, maybe

And as the inner doors are not there for extension, this should be a more simple system.???

[43Inches]

The answer is Yes and No,

The original protection mechanism is what you have described;

The 1 second delay cut-out only occurs if one flap is against a limit switch (fully retracted or extended) and the other is not.
If both flaps are off the limit switch then full assymetry can posibly occur.
Flaps on these aircraft are controlled by the two way switch, you hold the switch in the direction you want flap to travel and monitor the flap guage for position.

In serial numbers 31-7952001 onwards the system has a number of sensors which monitor both flaps position and cut-out the system if a split of 5 degrees or more occurs (no delay). These aircraft have a user freindly flap handle with detents for each flap stage.

However no matter which system you have the basic rules are the same;

1. Don't extend flap with autopilot engaged (it will mask the roll)
2. Extend flap in small increments at a time, Piper recomend no more than half second application in the old paddle type switch.
3. A further recomendation by piper on old models is use no more than 15 degrees flap if the flap breaker has a popping history as it indicates a flight load issue.

With the PA31 know what serial number you are flying and the difference between them. There are some critical speed and operating changes throughout the range even though they all look the same.

[Sillo777]

Doesn't the late model cheiftains have different system for flap, ie 1981 onwards have a flap computer in the avionics bay??, could be wrong but i am fairly sure they are different.

No more comment from me on this one though...:(

[Delta_7]

Flying Spike.

I'm a little amused that someone who came on here to

gauge the level of systems knowledge amongst those endorsed on the type

can't even tell me what the hand pump does on the ground. :=

Delta

[PA39]

I had an assymetric flap situation in a Chieftain (Flap rollers stick/jam on the tracks) its not a pleasant experience but certainly not a critical one. The aircraft ROLLS not YAWs and was reasonably easy to disgnose.Requested a C/L, and the bloody thing retracted once i touched the round........so a touch and go with ongoing clearances was requested and given. The thing just came out of a 100hrly there, so i wasn't giving it back to them..... Rollers and tracks worn and covered in grit.

[Atlas Shrugged]

Treat every flap extension as a possible assymetric extension.

* DO NOT operate flap with autopilot on.

* Extend flap in four 1 second stages.

* DO NOT reset the time delay relay in flight. It gives the flap another second of operation.

And if you do something and something goes wrong, undo the last thing you did!

[flying-spike]

I don't fly for a living any more and I haven't flown a PA31 for 17 years. I do remember some things and unlike some, don't profess to know everything.
If what I, and all the others that contribute here positively do know helps somebody then I am a happy camper and have a clearer conscience than somebody who sits on the sidelines and whose sole contribution is telling everybody how amused they are.
If I were you, and I am glad I am not, I would RTFM and by the way, I think everybody knows what YOUR handpump does on the ground.

[my oleo is extended]

Spike, It is 5 years since I flew a ‘31’ old friend. Sadly I had to give it all away after being diagnosed with the onset of epilepsy.

Nonetheless my fractured recollection of the ‘31’ is that it has two hydraulic pumps operate a common system which in turn are powered by each engine. Either one is capable of operating the system on their own, albeit at a reduced rate if need be. As has already been stated, most light twins have an electrically driven pump, but this is not always the case, dependent upon aircraft history. Once ‘gear up’ is selected and cycling is complete the gear handle pops back into its neutral position. But again as has already been accurately mentioned earlier in this thread, the gear handle will be slow to reposition if the engine is at idle or there is low power output. If you check the handle and it does not pop back into the neutral position then most likely one or possibly both the hydraulic pumps are faulty.

There were several occasions during my career when the gear doors did not close properly and a red gear position light illuminated. I simply lifted the handle from its neutral position to ‘up’ and that solved the problem and then popped back to neutral when the system is re-pressurized.

If all else fails then during maintenance try using Danish butter, not on the pumps but on your sandwiches. It makes for a tasty treat during long maintenance shifts and it is also handy for those handpumps on the ground!!

[No Body]

And if you do something and something goes wrong, undo the last thing you did!


Not necessarily - read your POH, as the flap abnormality checklist differs significantly between the Duke (older model) and Celco (newer model) flap systems.