Bolivian 727 lands short

[David Hilditch]

For our inaugural crash, let's note there was a Lloyd Aereo Boliviano 727 that yesterday apparently landed a few miles short of its alternate destination in the jungle, having diverted. Fuel exhaustion a possibility :

http://www.reuters.com/article/marketsN ... 201?rpc=44

http://aviation-safety.net/database/rec ... 20080201-0

[Robert Hilton]

Good to see everyone got out.

[Carlos G.]

We have a long way ahead of us, Robert, until sufficient members drop by this forum to get news about aviation themes. It depends on us to feed these threads with news and comments.

As far as I have read, the 727 hit bad weather and the alternate airports above minimums were too far away for the fuel the plane carried. Trinidad, where the 727 was heading to as an alternate, is some 600 km away from its original destination. That's almost one hour distance in flight time... quite a lot to carry extra fuel for such a long distance, especially for a company already known for problems with debts (speculating here, of course).

Another report: http://news.bbc.co.uk/2/hi/americas/7223673.stm

A "mechanical fault" affecting all three engines? Since we've had the BA 777 accident this seems to be a good excuse... unless the F.E. means by "mechanical fault" lack of the essential liquid to feed them...

and yet another one:

http://www.cbsnews.com/stories/2008/02/ ... ld_3779672

"We noticed the engines went out, and there was this calm," said Paolo Bravo, a Bolivian senator who survived the crash, in an interview with the radio network Erbol.
"Then they told us, 'Crash positions! crash positions!' and it was just another two or three seconds before we hit.

Unless I'm proven otherwise, very clear circumstances for me here.

[RadarContactLost]

Dash 17R engines, I imagine the airframe is write-off but the engines will be worth something.

[Carlos G.]

I don't know if ITS is reading this, but does anyone know if all three engines are fed from a common tank on the 727? All three silencing at a time is not so common, what do you guys think?

[Princess Leia]

AFAIK, all commercial jets that operate in the USA need to feed each engine from a seperate tank at certain phases of flight. I think the 727 qualifies.

[Carlos G.]

AFAIK, all commercial jets that operate in the USA need to feed each engine from a seperate tank at certain phases of flight. I think the 727 qualifies.

Than I find it strange for all of them to quit working at the same time, don't you?

[David Hilditch]

Than I find it strange for all of them to quit working at the same time, don't you?

Not if they ran out of fuel.

[Carlos G.]

Than I find it strange for all of them to quit working at the same time, don't you?

Not if they ran out of fuel.

You mean the crew kept selecting the feeding system as the different tanks got empty one after the other? Wouldn't it then have been wiser to shut down one engine (the central one) to burn less fuel since they were on the descent for quite some time anyway? Wild guessing here, maybe that's what they did.

[RadarContactLost]

Most 727s have 3 tanks (some 4) but for approach and landing you'd normally be "tank to engine." If you're low on fuel, say less than 3000 pounds, it would be all crossfeeds open and all boost pumps on. There are 2 pumps in each wing tank and 4 in the center with some pickups forward and some aft. You can un-port the forward pump by pitching the nose up too much but the other port should still provide enough fuel to run the engine.

[Princess Leia]

Dash 17R engines, I imagine the airframe is write-off but the engines will be worth something.

Looks like JT8D-15s, and you might have trouble selling thee ones that departed the airframe. #2 should be OK though.

[Dmmoore]

This one should be a short and sweet investigation as to finding the cause. It may be a little more difficult finding the reason for the cause.
The only mechanical defect I can think of would be fuel in a tank that could not be accessed. Most 727's have three tanks. The center tank being the largest. Takeoff is accomplished burning fuel from tank to engine (tanks 1, 2 & 3 feed engines 1, 2 & 3 individually). shortly after TOC the S/O opens the cross feeds and feeds fuel from the center tank only by turning off the fuel feed pumps in tanks 1 & 3 (first one, pause then the other). Fuel is burned from the center tank until the fuel in the center tank (tank 2) is equal to the fuel in the wing tanks (1 & 3). The feed pumps in the wing tanks are turned on and the cross feed valves are closed (one at a time).

Some 727 are equipped with an auxiliary tank. Fuel from this tank is pumped into the center tank as soon as possible after reaching TOC. If this fuel is not usable the aircraft can not proceed to it's destination because it no longer has the required fuel.

As RCL reported, low fuel condition, all pumps on, all cross feeds open, until fuel exhaustion.

I would idle 1 & 3 and use #2 only to adjust the rate of descent but that isn't in the book and may not be all that effective.