So how often are the bearings being replaced then?

Not Often, take a look at the photo's closely, especially the one with the rod end still attached with all the 'cocoa' around it, that does not happen overnight or even IN a week or two but takes time, looks to me that those bearings have not been inspected as per the AMP in the IETP.

Just my opinion!

S

Ground Taxi AW139
 

Greetings All,

I'm new here & I don't know if this has been discussed or not. However, I'm putting this question to have your valuable inputs & help sharing some information :hmm:

AW139 Ground Taxi;


What are the issues that might be encountered during wheel taxi?

What are the limitations on wind speed for cross wind wheel taxi, tail wind, etc?

How likely is it to run into rollover during wheel taxi?


Thanks

Maddam

Maddam: Read some comments on page 56.

Also check at 6 mins 40 seconds in the video below for wheel shimmy during taxi:

@hihover
 

for w&b in B412 & aw139 I do use pilotwizpro, iphone e ipad app.
cheers

Thanks!

Now,

How likely is it to get into rollover during wheel taxi AW139? :ooh:

Maeroda
 

Thanks very much, I'll take a look.

Maddam: Most blitterblats have a fairly high CofG .. engines, transmissions (main and engines), shafts, swashplates, hubs, heads, and rotors etc. all typically mounted above the cabin .. but this makes them 'vulnerable' when being towed more than during taxi. I say 'vulnerable' but the risk is minimal and I have never actually heard of an aircraft being rolled while being towed .. although I have seen them collapse while towed into or across something they weren't meant to encounter!

When taxiing (ie. under power) that 'upper weight' (ie. high CoG - often enhanced by low fuel and nil pax) is mitigated by the gyroscopic effect of the main rotor.

However, if you were to taxi as fast as you could and then boot in full rudder .. perhaps you could 'trip it up' but in fact if you did that .. you would most likely achieve a 'tail swing' which might (given how the 139 'hangs') result in a boom strike which could result in a roll over.

Well that's my thruppence worth but you should be advised .. I'm no expert on such matters!

ps: Speaking of gyroscopic effect .. it is possible (so I understand) to misjudge a run-on landing (which if you've had a brandy for breakfast could be interpreted as a fast form of taxi) whereby if you 'strike' one of the craft's wheels extremely hard it may cause the fuselage to rotate and if one of the wheels were to 'catch' any sideways movement while not properly planted on the ground .. then you will get your roll over.

Sav

Not an AW 139 but G-TIGL was rolled in high winds in Newcastle UK while being towed in the mid 1980s. I think that the main doors are opened now when towing in high winds.

Savoia,

Thank you for your effort ;)

Blow me over in the clover.......
 

......well I seem to remember BAH had a brand new S76 blow over in a gale on one of the Forties platforms. They had tied it down to the mooring rings set in the deck but unfortunately the welder has missed them out when the deck was built so they were only held in place by several layers of paint.

G.

Quote:

---

ps: Speaking of gyroscopic effect .. it is possible (so I understand) to misjudge a run-on landing (which if you've had a brandy for breakfast could be interpreted as a fast form of taxi) whereby if you 'strike' one of the craft's wheels extremely hard it may cause the fuselage to rotate and if one of the wheels were to 'catch' any sideways movement while not properly planted on the ground .. then you will get your roll over.

---

Do you mean something like this?

That doesn't look dynamic roll-over to me. They lifted off and start spinning, they didn't roll-over. Most likely it was a tail rotor trouble or whatever. Anyway not a dynamic roll-over.

Definitely a tail rotor issue.

Puma...flared tail into the deck:ugh:
Got airborne again:D
Soldier/policeman in the back spat out, nearly landed on, legs it into the distance before the tail comes round to mince him...well done:ok:
Pilot re-briefed by pax:ouch::mad:

Dynamic rollover during ground taxi.
 

Maddam asked:

"How likely is it to get into rollover during wheel taxi AW139?"

Any wheeled helicopter is likely to rollover during ground taxi operations if the pilot mishandles the controls. See this accident report on a Dauphin 365 N3 http://dgca.nic.in/accident/reports/VT-SOK.pdf The pilot chose the wrong option i.e. he raised the collective instead of lowering it, when the incipient symptoms were recognised.

Another rollover accident to a wheeled Bell 214ST in Saudi Arabia (ex ROP machine) also comes to mind. I cannot find that report but I am aware that the commander did not have time to intervene when the copilot pulled pitch during the turn into dispersal. The wheeled 214ST had only been added to the fleet of skidded 214B models the week previously.

All 3 types AW139, AS365 and Bell214ST are safe to ground taxi if the pilots are aware of the causes of dynamic rollover and apply the correct techniques to prevent it.




speds

Availability
 

What level of availability are people getting from their AW139s in an EMS role?
Is 80% too low?

Resonance,
From what I hear 80% is above average.

Right on Speds.

We started wheel taxing AW139s & I've seen pilots moving cyclic with every turn! In addition to using 25 PI ;( . Sharp/tight turns where you think that the nose wheel would get stuck!! Some yank the cyclic & you feel the aircraft leans excessively.:ugh:

One of the most difficult things to get people to do in training is NOT to move the cyclic laterally during ground taxy turns. There is a lot of control power in this helicopter, and you dont want to introduce unnecessary sideways forces on the ground.