Piper Navajo N80HF accident North Weald
 

Evening all,

If anyone has any information surrounding the landing accident of Piper Navajo N80HF at North Weald earlier this year could you please PM me, it would be very much appreciated!

I have genuine motives for seeking this information, so if anyone does want to know before passing anything along please do ask and I shall let you know via PM :O

Many thanks,


Ox

What do you want to know and why...?

After having an interesting chat with people at North Weald, I have learnt that for the undercarriage systems to be operable on a Piper Navajo at least one of the engines must be operating, and N80HF landed gear-up on the 25th July 2010. Of course, the undercarriage could be deployed using the emergency extension procedure for that aircraft, although I can imagine that might be quite difficult whilst dealing with a double engine failure.

From one look at the aircraft (it's sitting outside at the Squadron) you can tell that it has clearly had a gear-up landing, although interestingly on both propellors two of the blades are damaged with the third being untouched, and there is no obvious deformation of the shape of the blades to suggest that they were under power at the time of impact. Correct me if I am wrong but I believe that the only situation that can cause both engines to fail simultaneously is a lack of fuel. How very interesting.

Thank you for those who have PM'd me so far, but if anyone does have more information or a witness account of this forced landing it would be very much appreiciated.

Kind regards,


Ox

“Correct me if I am wrong but I believe that the only situation that can cause both engines to fail simultaneously is a lack of fuel”

There have been double engine failures (almost simultaneous) on commercial jets, which were not fuel related, but due to very unlikely events or shortly after maintenance or modification.

Rod1

Also icing, fuel contamination, a catastrophic failure of one throwing parts & causing damage to the other, interference with controls/switches, failure of one + procedures while operating on one engine resulting in failure of the other (probably not simultaneously but landing with both engines stopped doesn't necessarily imply simultaneous failure).

There's five off the top of my head + what previous posters have written. Shall we have a competition to see how many reasons can be devised?

It might just be the pilot pulled both mixtures to ICO because he knew he was landing gear-up and wanted to save the engines more damage than necessary.

Very likely that he may also have positioned the props for the same reason. If you have to go in gear up it's a very sensible thing to do. Minimises damage.

I was going to say the same thing. When landing is assured, why not stop both engines so save shock loading the engines.

I tend to agree with most other comments here. Running out of fuel is the least likely purely on chance.

More likely running out of fuel would cause an off airport forced landing. Too unliklely but not impossible for the fuel to pick short finals to run out.

Fuel starvation is another matter as there were some double engine failures on the Golden Eagle caused by the fuel pumps going into the hi setting and causing both engines to fail. I believe the 340 as well as the 303 had the same pumps?
Dont know if the Navajo has such problems!

Failure to extend the Gear normally or by emergency gear extension methods would mean that the pilot would likely cut both engines to save shock loading once assured of landing on the runway or grass.

Pace

It won't save a legally mandatory shock load inspection IAW the engine mfgs requirements (unless one is a real cowboy and basically forges the logbooks :) ).

The vast majority of shock load inspections find no damage but most of the cost is in the whole dismantling + NDT job so the cost saving from shutting down the engine is minimal.

Also most 3B props mandate a scrapping of the hub if 2 or more blades are damaged to an extent requiring removal, and economically you are looking at new prop(s) anyway. So now you have two zero-timed props and if there was no shock load inspection you will have an engine logbook telling a different story, which very few buyers will believe.

10540
Shutting both engines down is a good idea before touchdown on two counts! It will save internal damage regardless of whether the engines have to be examined and it will reduce the danger of high speed bits of prop entering the cockpit and killing someone as happened in the humberside Golden Eagle prop strike on go around.

So for your own safety shut down before touchdown

Pace

It is not at all clear from the accident record that shutting down the engine(s) is a wise move when making a gear up landing.

There certainly are cases where the engine was 'saved' but there are also cases where the pilot spends so much time faffing about bumping props etc that he stalls the aircraft or misjudges the shutdown point and lands short.

There may also be cases where idling props break off on ground contact and injure someone (although I am not aware of this ever happening). I am aware of fatalities when a prop driven at full power hits the ground during a botched go around.

MM

The Golden Eagle was a go around prop strike under power.
Sadly a piece of the prop entered the cockpit killing one of the occupants. Nevertheless it shows that there is a lot more energy to do damage if the prop is under power on striking.
Most gear up prop strikes are due to gear failure.In such an event burning off fuel is sensible hence a diversion to a large runway with good emergency services and preferably foam to avoid spark fuel ignition is also sensible.
As such landing short would not be a problem to an experienced pilot.
Cutting the engines at 50 feet when landing is assured would be far safer than landing under power.
One pilot flew over a van with an engineer on the back who pulled the one undercarriage leg down and there are other examples of creative piloting.
I don't consider much risk on cutting the engines unless a poor pilot is at the controls

Pace

Crashing an aircraft with fixed undercarriage and a ballistic parachute is quite an achievement.

I suppose it depends what caused the double engine failure. Mistakes with crossfeed can do this as can fuel mismanagement, amongst other things.

I'd say walking away from an single engine aeroplane with a failed engine in flight is a rather good achievement...

Funny how people just pop up with a post count of 1 and making some point against somebody else :)

Well spotted :rolleyes: and I accept that any landing you walk away from is good and if they can use the 'plane again............

Funny how you made that your 12,001st post ;)

I know; it's really scary...

Report out.

I found it very interesting reading. A very large degree of bad luck, handled well by what reads to me as a very competent pilot.

Fuel starvation because of abnormally high fuel burn (more than 20% greater than the POH, which the pilot had already allowed for), combined with an even worse than usual fuel gauging system - then handled impressively well by a pilot who managed a very well performed gear-up landing from an engine failure at 1000ft 2 miles out.

I don't believe that I know anybody involved and have no axe to grind either way - but it really does come across to me as very bad luck, handled very well once it had happened.

G

I understand that this aircraft has now been sold for salvage. What's the use in salvage of an aircraft of this age.? I can't imagine that there are many of these around now due to the high fuel expense and a cirrus will do the same speed on less than half the maintenance cost I imagine.!:hmm:

the human head weighs 8 pounds aswell. Which is about as significant.

I just meant would someone go to the bother of rebuilding something like this aircraft or what would you do with it.? I doubt there is much of a market for them thats all.....

Rebuild by someone with their own labour or cannibalism for parts? If the insurers' write off threshold was low enough, someone may think they can get it flying with a reasonable margin.

I'm not an engineer, but I would imagine that there would be a fair amount of commonality of parts for various models of Piper of similar vintage. For the rest, considering the amount of road signs going missing these days, the metal content alone has a value.:(

So long as the hull and the wings aren't bent, it can be repaired if the insurer sells it cheap enough (say under £10k).

The report is interesting for its scandalous disclosures of previously little-known gems like this

I always thought that this kind of knowledge ranked with masonic secrets, where the Nazi gold is stored, whether the US has UFO wreckage and alien bodies, and whether the NSA has found a way to rapidly factorise products of large primes :)

I would replace "many" with "practically all".

I can finally appreciate why the AAIB job adverts say you need to have an ATPL, which they will keep current for you.

It does amaze me (well actually it doesn't) that people are still doing "serious" flights like this, without a fuel totaliser linked to a GPS. The totaliser costs about £2k to install, less on an N-reg, and the IFR GPS you probably already have. Then you get a constantly recomputed "Landing FOB" figure. Then you know what you've got instead of relying on data in a decades-old POH.

The best fuel gauge in the world is usually a sight gauge - incredibly easy to design into any high wing aeroplane.

Hard on a low wing twin like this of-course, but would be dead easy on most Cessnas, for example. Most microlights do this because it's cheaper and more reliable and more accurate than anything electronic - presumably light aeroplane designers think that their customers want to pretend they're driving a car?

G

A sight gauge only tells you what you actually have, which is no good if you are enroute to somewhere and do not even know your precise fuel flow rate.

This is the system I refer to. It is very common in the better IFR tourers. I routinely land and fill up within 1-2% of the computed figure, and would never do my 900nm+ flights without it.

When I see bigger errors, it points to a pump which has been "adjusted" in favour of the airport, in a country where Weights & Measures inspectors are nonexistent ;) The biggest errors I have seen were ~ 5%, in Greece and Italy.

Anybody pushing to say 80% of their best dry-tank range, without this kind of equipment, is going to get their bum bitten eventually. Some stories I have heard have been truly scary, but the ones people talk about are the ones they got away with. Like one pilot who landed an old TB20 after a 1150nm flight with a few USG in the tanks.

I don't think many microlights do flight of significant distance, so they don't need to worry :)

Problem with many fuel totalizers are that they only count the fuel that goes to the engine. Many engines, like mine and other Lycomings, "overfeed" the engine and then has a fuel return that goes back into the tank for the stuff it doesn't use. So you need two measuring points, one additive and one subtractive - most totalizers don't do this.

That would be a useless and negligent installation.

I don't think most Lycos do this though. Mine doesn't. Conti engines tend to do it.

It's really not that hard, if you have an accurate fuel gauge, you just track fuel consumption on your PLOG along with time and distance.

Having done quite a few multi-hour microlight trips, I reckon to be accurate to within a couple of litres of what it'll be at any point forwards once I've been flying for half an hour or so.

A light aeroplane, with the well known dodgy fuel gauges, does require more guesswork, or the sort of system you're talking about.

G