AvWeb report into Whyalla - Labelled as 'Popycock'

[Tas661]

PA31 Drivers

G'day People,

Im doing a Chieftan endorsment in about a month.

Do any regular drivers have any hints/tips/rules of thumb that make operating the beast a little quicker or easier ?

Ive read the manuals but Im after some of the more practical info that they dont publish !

Thanks !

[Careful McTavish]

Set trim 4 wind rearwards from full nose down.

Make sure engine driven fuel pumps are supplying at least min pressure before
turning on low pressure pumps,they can mask a problem.

When starting 1st engine,push down gear lever
to test hydralic pump,and shut this engine down 1st and test other engine after flight.

To open gear doors,pump emerg ext handle 2-3 times,to close turn on master and pump,or start engine and select geardown.

24" 2300 on downwind
30.5" 2300 in cruise 19gph approx

Keep 10L in aux tanks for emergency fuel probs.

Enjoy them,nice plane.

[Capt EFIS]

The PA31 have bladder fuel tanks, as quoted in the POH it is advisable to leave a little amount in the aux tanks, and I guess 10lt could be enough.

Never leave the fuel cells completely dry, or the cell inner liners may dry out and crack, permitting fuel to diffuse through the walls of the cell after refueling. If the cell is to be left empty for a week or more, spray the inner liner with a light coat of engine oil.

Cheers,
Capt EFIS.

[Careful McTavish]

When the refueller comes around,get him to put 10L in the aux tanks,if the main tank lines are blocked for any reason,you can have a few mins on the aux to sort it out.

If you turn the boost pumps on as soon as the engine starts you will not see if the engine driven fuel pumps are working.

I have seen this happen,one engine was indicating 17psi,but went to 35psi with boost pump on,not good in an electrical
failure.

[FO Cokebottle]

This debate could rage on for ages.
Anyway some useful operating tips for the driver (not the technocrate).
1. When planning decent inbound
a. allow 2" per minute power reduction to 25"
b. plan a 2 minute straight and level segment at cct height/LSA/MSA prior to destination.
c. This one is especially useful in CTR (with inevidable late clearance for decent is expected to LOC for ILS)- 1 minute before planned T of D extend flaps 5 degrees (max). This will bring speed back to about 150KTS when on decent (profile 800'/min) speed will remain below 155KTS.This is more manageable than 190KTS and prevents blasting over the LOC at 170 - 180KTS with a battle to lose 50 to 60KTS to drop the gear(Vlo 129KTS).

Always read the POH (limitations) before blasting off. PA31's manufactured ofter a certain date/serial # have a higher Vlo (158KTS) than the earlier models (129KTS). Owners don't like you ripping off flipper doors when you drop the gear at the higher speed by mistake.

[john_tullamarine]

I would be very careful about making inferences regarding unusable fuel. The standard tests made to determine that value are reasonably conservative. In many cases the routinely "usable" fuel will include part of the AFM-specified unusable quantity.

[daytrader]

Have another look at the split flap scenario in the POH. I think a fully assymetric split condition is uncontrollable.
Longer than usual time for the gear selector to return in the hydraulic test indicates possible impending hydraulic failure.
The turbos never kick in together on T/O, expect yaw. 30" before brakes release helps.
Trim back a bit more than you think before the flare to assist with reduced evevator authority.
Use smooth boost reduction on descent and min pwr on taxi to minimise cool down wait before shut down.
Do a search, there's been a couple of good threads previously.

[ 22 November 2001: Message edited by: daytrader ]

[The_Hun]

I have been informed by my father that twin piston engine aircraft are dangerous and unsafe.

In his opinion they should not be used for the carriage of fare paying passengers as it is probable that they will crash in the event of an engine failure.

This is yet another reason why I want to go straight into an airline when I finish high school.

[Capt EFIS]

The_Hun,

Does your dad work for CASA ??

[Bob Hawke]

As cabin crew???

[I'm with stupid]

Bad news for ya Hun, no matter what you do aviation wise when you leave high school you will have to do at least 20-30 hours in a piston engine twin that is nowhere near as capable as the Chieftain, how do you like them apples ?

[VOTZEboy]

Hun,back to the sand pit little fella.Thats a wind up if i've ever seen one,don't take the cheese boys!

[Checkboard]

For the pre-flight, in addition to the items in the manual, here are a few PA 31 tips:

• As mentioned above, just before the pre-flight in the cokpit, push the gear handle down, and pump the emergency gear handle a few times to lower the main gear doors. This checks the operation of the emergency pump.
  
• Check the main cabin door striker plates, and the actuation and security of the door handle - a weak point especially in older aircraft.
  
• On the engine, open the side access hatch and check for cracks of the exhaust pipe near the y-bend aft of the turbo charger.
  
• If the engine is cold! Check the security of the pipe itself (one came off in my hand one day, and a failure here will direct hot exhaust gas at the engine firewall). At night, you can see the exhaust glow red through the inspection port from the cockpit.
  
• Check the engine cowl security. The front of the cowl is held in place by two fairly short pins on the far left and right of the upper cowl. It is easy for these pins to be misaligned if the cowl has been removed and refitted, with the cowl appearing to be in place, it will depart the airframe in flight.
  
• Be careful when using the oil dipstick checking the oil to use the correct scale - the dipstick is marked on both sides, one side for the left engine and one for the right.
  
• If the fuel cap locks are stiff, a little oil dripped onto the lock hinge from the oil dipstick will free them up nicely
  
• Check the main gear down locks and the uplock hooks and rollers for freedom of movement. The uplock rollers can rust up, causing the gear to hang.
  
• Evidence of leaking fuel cells (bladder tanks) may be seen around the screws at the wing root fairing as a blue/green stain. If this is the case, fuel vapour will have collected in the wing root fairing, and may be ignited should a backfire occur on start causing an explosion. This has happened twice in Australia that I have heard of.
  
• Check the crossfeed on taxi out (you do anyway, don't you?) in order to remind you of the crossfeed procedure. Remember that the fuel pumps "belong" to the repective tank, not the engine, in that crossfeeding from the right tank to the left engine requires the right fuel pump to be on (not the left!)

A few operating tips:

• When you start the first engine, the hydraulic pump will operate, closing the main gear doors, and returning the gear handle to Down-Neutral. This checks the operation of the engine driven hydraulic pump. To check the pump on the other engine, either alternate the engine you use to start, or shutdown the engine you started first, push the gear handle down and watch it return to Down-Neutral (at 1200 RPM, the handle should return within three to nine seconds), then shut down the second engine.
  
  A slow return to Down-Neutral of the gear handle may be an indication of a worn pump or an impending serious hydraulic leak.
  
• Landing on a muddy runway can throw mud up into the flaps,fouling the flap micro-switch located behind the gear (you can see it when the flaps are down). This will result in the flaps not being able to retract. Cleaning the area can solve the problem.
  
  You may have to reset the flap circuit breaker in order to reset the flap time delay switch (the assymetric flap protection).
  
  If all else fails, the flap relay is located in the cabin floor between the flaps - I once had to jump past the relay in order to retract the flaps and get home. Don't know that I would recommend that - but if you do, be careful not to overrun the flaps as the motor won't stop when the flaps are up!
  
• If you need ground power to start due to a flat battery (master and electrics off during start), remember that the battery relay requires battery power to close - so if the battery is flat, even though the aircraft is running and powered, the battery will not charge.
  
  Before shutdown check that, with all electrics off and the engines at 1000 RPM, the ammeter is showing the battery charging at less than 25 amps in order for there to be enough power for the next start.
  
• It is possible to obtain an excessively rich mixture if continous flow fuel pumps are used at the same time as emergency (boost) pumps, although this shouldn't occur if the fuel control unti is correctly set.
  
• Many ammeters on these aircraft operate poorly, a good cross check of alternator voltage is to turn on the cockpit dome light and check for brightness.
  
• It is possible for the prop governor to freeze in icing conditions, if you use 2200 - 2300 RPM for cruise, your power will be limited by the Manifold Power restrictions.
  
• The left alternator belt can slip in moderate to heavy rain, causing a low voltage light.
  
• A leaking left cockpit window can allow water to drip into the CB panel, causing a total power failure - including battery power.
  
• The fuel consumption figures are a bit understated in the manual. so holding times and best economy fuel flow rates are only obtained at peak EGT, and sometimes not even then. Be conservative in planning fuel, and don't trust the manual's figures!
  
• The EGT pointer can stick, and a sudden drop in Manifold pressure may be a lose pointer - if these occur, look for a secondary indication (like yaw) before jumping to conclusions!
  
• Like all bigger Lycomings, the engine can be a lttle difficult to start when hot. The best technique I found was to close the throttles, hold the mixtures at idle cut off, and run the fuel pumps for five or six seconds to flush the lines with cold fuel, removing any vaporised fuel in the lines. (The fuel travels from the tank through to the engine to the fuel control unit, then returns to the tank as the mixture is at idle cut off.)Turn off the fuel pump, then move the mixture from cut off to full rich and back to cut off - you will see the fuel flow indicators jump a little as a small charge of fuel enters the cylinders.
  
  Open the throttle a half inch or so and crank, if the engine doesn't start within two or three rotations keep cranking and open the throttle fully. It should start nearly immediatly.
  
  As soon as it fires, increase the mixture to full rich and quickly close the throttle to idle.

Note: The above is from memory, and I haven't flown a Navajo for seven odd years, so take it all with a grain of salt, and ask your instructor!

Apart from that I like the aircraft. It is big and stable, good for IFR work and handles a load pretty well. Have fun!

[ 22 November 2001: Message edited by: Checkboard ]

[Mainframe]

Try to do a load check particularly with your load tending toward aft C of G so you can experience the porpoising ( phugoid ) oscillations at climb speed. The aircraft tends to be a little unstable in pitch until you can afford to increase CLIAS (above LSALT). Be aware of this characteristic coz it could cause you some concern the first time you're in that configuration (e.g. PJE ops)and didn't know it's normal.

[Grogmonster]

HEY HUN, Chieftains fly well on one engine even at weights near max. Take it from someone who has been there.

[hannah]

The Hun,
Are you really serious or just post for a chuckle??
Aren't you doing a degree in aviation?
I am curious to know what type of aircraft you are actually going to learn to fly, maybe you will be the first in Australia to hold a 737 PPL? I really hope that your posts are just a wind up because if they are not you are in for no smooth trail, because the amount of disrespect you show for the system are going to be like huge speed humps along the way,sorry.

[Hightower]

The Hun
Haaaa Haaarrrrrr.
Funny.

[Checkboard]

Yes The Hun just posts for a (rather inane) chuckle. If you perform a search on his member number, you will see that each post is exactly the same in content.

[Mud Skipper]

HUN, you crack me up.

Seriously though, of all things that use to bit me was people not shutting down the heater and tripping the overheat. Operating in a cold climate this was a real pain as it can't be reset inflight.

Also do the owner a favour and abide by the engine/egt cooldown on the ground. You can get away without 1 inch per minute in the approach as long as you give it around three minutes cooldown on the ground and get the egt down, saves the turbocharger.

With thousands of hours on this type I'd say it's a great aircraft.

[bboy]

Has anyone had a problem with engine surging ?
Had a 100-150rpm fluctuation with LH engine the other week in flight. Subsequent ground run revealed no problems and hasnt occured.

Believe the PA 31 is prone to low prop dome pressure, leading to govenor "hunting".