PPRuNe Forums - Dili incident

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- - Dili incident (https://www.pprune.org/pacific-general-aviation-questions/638065-dili-incident.html)

Landed with the park brake on?

Or more likely the anti-skid off.

Most likely anti-skid not on; possibly. If the brakes were on and there is no reason for them to be on the rims would have been ground down flat.
The Lear 60 has to be handled carefully; From memory I seem to recall the tyre pressure is ultra critical. There are only two other types where the tyre pressure is higher and I think they are the B747-400ER and the B2B bomber.

Will make very interesting reading when BASI have done with this. There has been one or more fatal accident in the Lear 60 directly due to low tyre pressure, tyre failing and damaging hydraulics when retracted.

Is the anti-skid selectable to on/off? Or is it like most aircraft, where it is always on and a mechanical failure will cause it to turn off?

It is selectable, and part of the pre takeoff checklist.

https://reports.aviation-safety.net/...J60_N999LJ.pdf

This is a good read.

Quote:

Originally Posted by chimbu warrior (Post 10970030)

It is selectable, and part of the pre takeoff checklist.

https://reports.aviation-safety.net/...J60_N999LJ.pdf

This is a good read.

My goodness, what a sobering read.

Of all biz-jets, the Lear 60 has the highest accident rate on landing; sometimes fatal.
Extremely high tyre pressure, essentially on a Lear 20 wheel/brake assembly.
I believe it is a requirement for tyre pressures to be checked daily, if not weekly (FAA)

Quote:

Originally Posted by Petropavlovsk (Post 10970073)

They are not a good example of the LJ's, too many limitations. The 40 series are the pick of the bunch and oh so easy to drive -)

From the report above:

Quote:

The characteristics of the sidewall damage observed on all four of the accident airplane’s tires were consistent with a photograph in a Goodyear publication showing typical heat damage sustained from sidewall overdeflection and flexing fatigue. Goodyear engineers and the Goodyear publication noted that previous tire testing found that aircraft tire sidewall damage from flexing fatigue is predominantly consistent with taxi-cycle operations while the tire isunderinflated; Goodyear testing showed that as little as 5-percent underinflation greatly reduces the fatigue life of transport-category aircraft tires.
...
Other damage observed on fragments from each of the accident airplane’s tires included blue to purple heat discoloration indicative of moderate to severe heat damage. According to the Goodyear publication, blue tinting appears at temperatures from 210° to 230° F. Microscopic examination of fragments from all four tires revealed that the tires’ nylon fibers (which are generally soft and fabric-like when undamaged) had melted and resolidified into single strands that had a stiffness resembling that of broom bristles. The Goodyear publication noted that the melting point of nylon is greater than 400° F. Rubber reverts to an uncured state and loses strength and adhesion at temperatures from 280° to 320° F, then becomes hard and dry at temperatures from 355° to 390° F.

given that all four of the main tyres in the Dili aircraft failed, and they look like sidewall failures, it does point to overheating from under inflated tyres.

The report also says:

Quote:

The contents of chapter 12 of the AMM related to technical specifications and descriptions of how to perform various maintenance tasks. Chapter 12-10-05, pages 301 and 302, contained the following guidance:
Important inflation practices and tips are as follows:

... Measure the cold tire pressure before the first flight of every day or every 10 day[s] on in-service tires [that] are not in use....

Do not underinflate the tire. An underinflated tire generally cannot be detected visually.

The AMM indicated that a tire should be replaced if found to have operated at an inflation pressure loss of 15 percent.

Sobering reading of that 2008 LJ60 report indeed!
5% loss of pressure per day means your tyres/tires are going to be out of specification very quickly, especially in these times of covid reduced flying times.
Pressure checks to be done whether operating under part 91, 121 or 135.
One blown tyre/tire makes the other one out of specification. Any sideways forces will add to the strain on the sidewall.

Appears to be lots of cheese holes in near alignment in normal operations.

Will be interesting to see the background causes of this incident.

Townsville refueled said a head strong, green, Deputy CP, who didn’t fully utilize CRM to take advise from several people not to go there. But to go to a more wx predictable destination.

Flight trackers don’t show the final track, but heard there were a few attempts to land in average weather.

glad to hear everyone walked away from this one.

The Townsville refueller runs ring around them ATSB blokes!

Quote:

Originally Posted by turbantime (Post 10970067)

My goodness, what a sobering read.

Not wrong, talk about every hole lining up!

Quote:

Originally Posted by ContactMeNow (Post 10970855)

I believe Deputy CP may be green when it comes to the LJ60 but quite experienced aviator in general.

Not the first and won’t be the last to try landing in average weather.

No one hurt and aircraft can be repaired, Could have been a lot worse.

I’m sure the crew will both have learnt something which they’ll be able to fall back on when they find themselves in a similar situation

(S)Careflight aircraft?

DF.

AVCAIR PTY LTD PO Box 114 HAMILTON QLD 4007 Australia, Careflight from my observations run a tight ship.

Careflight ( Lifeflight ) / Avcair are like cheese and chalk
Lifeflight are a specialist medical retrieval organisation whereas Avcair is a GA charter company

Propjet and Duck Pilot:

You're probably correct - my post withdrawn but a PM sent...

Thanks for doing the right thing Dora-9