let off the runway in tz

[406pilot]

hi there folks....

this happened on sunday as we were about to depart for jhb ,i noted a tip tanked high wing airplane parked on the left side of the runway 23..anyways did some investigation and mostly gossip and found that it was a let(again) belonging to zanair that had gone off the runway due to wht was called brake/hydraulic failure...always thought spoilers/beta would be enough to stop this stol aircrafts..but then i guess i have been wrong in the past..needless to say that the names of the crew are withheld but as usual the pm lines are open to those of you who wish to pass on their PFS regards....

keep it up there fellows,

no more 406pilot....(thank god for that)

[Woof etc]

The Let has an hydraulic accumulator in the braking circuit to allow braking following hydraulic system failure - the main hydraulic circuit being isolated from the braking circuit by a non-return valve. Braking is also available using the hand operated park brake which also has its own small reservoir. Nosewheel steering is hydraulically activated, so steering following hydraulic failure is by differential braking or differential reverse if pressure is lost in the brake circuit as well.

Reverse and spoiler application will be enough to stop the aircraft if the runway is of average length.

Of course, finger trouble would not have been a problem as it would not have been in the recent gear up landing.

[ShenziRubani]

A ha. Aaaaargh!!!!! Again. :mad: :}

[Soap Box Cowboy]

Use of Aesimetric thrust should have kept the plane on the runway, that and rudder and nose gear inputs whilst at a high enough speed for the rudder. Just release the brakes, plenty of runway like 406 said. Unless they were trying to make a turn and slaming everything hard. But then if you are making a short field and one side of the brakes fail or engine doesn't go into beta or reverse how long do you need to react. It's a big runway, long and wide, how far off it where they? And how is the aircraft? Never really heard of Karls Let's having too much trouble's unlike another company. Let's are getting a bad rep in Tanzania, could use some more details on this incident.

[Solid Rust Twotter]

L410s have been raining out of the sky all over Africa for years. Nothing new....:(

[406pilot]

hello fellows....

its true that the other company is phasing out their machiner the easy wy but dont think zan...has any plans to phase out these aircrafts in the near future..anyways the plane was parked near the very end of runway 23 and from the looks no great damage done to the hull...

by the way mr.cowboy i have been around to see the most experienced fellows bent the most robust of planes so do not be surprised buddy,just be prepared...hows your wing??

keep it up there fellows,

no more 406pilot

[Soap Box Cowboy]

The wing is healing nicely, will be back on the 29th, looking forward to getting up in the air again.

[Aviamil]

Hi,

Any news on a registration please, I try to keep an eye on all Let -410's in that part of the world.

There was another Let accident a few weeks ago as well, Any idea on an id of this one too.

Regards
Marc

[Solid Rust Twotter]

Heard of three L410s having accidents on one field somewhere in the Sudan in the last month.

[406pilot]

helo guys just when you thought it couldnt get any worse here is some serious gossip....he he he

had a chat to one of pilots at "tanzania's finest airline" and he told me that the dukes of hazzard had actually landed deep in an effort to force the landing as there was an aircraft on the runway waiting to vacate the active....interesting fact or fiction ?? if the pilot survived you will never know the truth...funny enough at the control were 2 captains who have had past bush flying experience so i very much doubt the fact that they could overrun a 3km runway...but it must have been done before sounds too damn familiar


keep it up there fellows,

no more 406pilot(and there isnt a day that i dont thank god 4 it)

[SA Fred]

The S Sudan strip (near Leer) apparently is the latest site for 410 spares... Once did a wheels up this month; the "rescue" one arrived and both airframes bonded; and a few days ago the third lost a nosewheel...

[Woof etc]

Unfortunately there are a number of operators in Africa that bought cheap former Soviet Union Lets and operate them with complete disregard for the prescribed maintenance schedule.

Typically these aircraft have components with no traceability and engines that are operated way past TBO. I know of aircraft operating in Mozambique for instance, where there is no engineer in the field to support the aircraft. Part of the prescribed maintenance program for the LET is a 10 daily inspection - who does this in this case? Usually these aircraft are registered in countries of convenience where a couple of bob slipped under the table gets you a C of A.

Unfortunately these rogue operators, operating aircraft the factory has no interest in being associated with, bring the aircraft into disrepute. The LET, if properly maintained, is an extremely durable and reliable aircraft.

As for pilot competency - the LET is a reasonably complex aircraft and requires a proper type rating with a good technical. I know of pilots that have been signed off P1 after a quick hop around the patch with no technical - criminal as far as I am concerned.

[406pilot]

hello fellows,

i have never flown the aircraft in question but i couldnt agree more with "woof" as i know several operators in TZ opted to buy 3x let410 and claimed they cost less then a brand new c-208...so as far as economics go its a wonderful 19pax twin turbine aircraft but as usual theres a catch to everything nowadays...and a few of the guys flying with "tanzania's finest airline" also proud crashers of 3 of such samples told me that that carryig 19pax out of 4500;elev airstrips really put the fear of god into them..in fact there was a time when they went up to do "c of a" test flight and the aircraft failed to climb away with one engine feathered...all this and the fact that the wipers are hydraulically operated,its a nice and durable aircraft...yeah right

keep it up there fellows,

no more 406pilot

[Woof etc]

"all this and the fact that the wipers are hydraulically operated,its a nice and durable aircraft...yeah right"

As you say, you have never flown the aircraft.

I say again, a PROPERLY MAINTAINED Let is an extremely reliable and robust aircraft. I state this based on my 1500 hrs experience flying properly maintained LETs. If you want to fly rubbish FSU aircraft with no maintenance, no maintenance records, engines way out of TBO bought for a dime a dozen and registered in some dodgy Banana Republic - well it's your sickleave. Even the LET factory does not want to be associated with these aircraft. Unfortunately, a number of these aircraft seem to have found their way into the backwaters of Africa.

A new Let 410 UVP-E20 will cost in the region of 2 million USD.

If the aircraft is operated within the manufacturers parameters, it will perform as advertised. The aircraft will climb fully loaded on one engine at 4500 ft if flown correctly. However, if you don't clean up the aircraft and fly at the correct speeds, like many aircraft, it won't climb. In an actual emergency, the power levers are lifted through the gate and the maximum ITTs and torque can be exceeded for a period of 5 minutes to provide an emergency power reserve. This obviously cannot be simulated during training.

Going back to the example stated in Sudan. How exactly do you land a LET wheels up? Either the gear warning is inoperative or both pilots are completely deaf - believe me you will know about it when it goes off. Landing deep and hitting the first aircraft? A competent pilot can put a LET down in 250m. Nosewheel falling off? That tells you everything you need to know about the maintenance of the aircraft.

Aviation-safety.net provides some insightful statitics:

Of the 28 listed hull losses to Let aircraft since 2000, 14 of these have occurred in Africa - virtually all can be attributed to pilot error or poor maintenance. Of the 5 hull losses recorded last year, all of them occurred in Africa! The latest incidents mentioned above will contribute to Africa's quest to destroy aircraft as fast as the developed world can produce them. Aportion blame where its due, it ain't the aircrafts fault!

The Let is most commonly compared to the Twin Otter. Aviation-safety.net provides the following comparative statistics:

LET 410: Production commenced 1969
Number Produced 1138 +
Hull Losses 73 (6.5 %)
Fatalities 277

Twin Otter: Production commenced 1965
Number produced 844
Hull losses 216 (25.6%)
Fatalities 1222

Like any aircraft the LET has its limitations. You can't put 19 pax, luggage and full fuel in the aircraft and expect to be within the weight limits. Baggage capacity is limited. The aircraft could be lighter, a consequence of it's brick sh_thouse construction.

However, flown within the design parameters and correctly maintained, the LET is a reliable, safe and economic aircraft to operate. That's probably why it is the most prolific twin turbine in Africa.

ps. The hydraulic windscreen wipers work just fine - been very grateful for them when flying an approach in a west African thunderstorm. Besides, I can assure you that they are a lot better at removing Siberian winter icing than the wipers on your aircraft!

[Renaissance]

Hey 406,

There you go again upsetting people ;-) The Let is flippin awesome dude!! Back to the original subject, did one of the crew woek where you are now? No names....

Hey Soap Box,

How does one break a "wing" pushing a Caravan? Anyone who worked for DHL on B757s would never manage that. Unless of course its an excuse to go to the middle east for time off :-)
I am fishing. Check your email......

[406pilot]

hello there kj...

you are right about one of the pilots....just got ur sms...the plan is to ferry her next month at the same place.

anyways i never meant to upset anyone, us being humans are entitled to our opinions...like a few of us that enjoy safety and speed others will keep on enjoying robustness and effective wipers while still cursing the design flaws of this overweight designed plane...

anyways wasnt this "flippin awesome"...robust plane have an airframe lifetime of around 5000hours or so??? and didnt someone say that this so called robust plane was never certified in any of the developed countries?? or am i missing a point here...he he he

keep it up there fellows,

no more 406pilot

[Woof etc]

406pilot

Sigh. You're not a big one for facts.

Airframe life 5000hrs? Want another guess? Actually it's 20 000 hrs which may be extended by modification.

Here some more facts that would be of no interest to you:

"The L 410 UVP-E aircraft and its derivative versions meet the NLGS-2, JAR 25 or FAR 23 requirements. Certifications have been obtained for operations all over the world including Argentina, Australia, Brazil, the Czech Republic, Colombia, Cuba, Denmark, Germany, Chile, India, Indonesia, Kenya, the Philippines, RSA, Russian, Sweden, Ukraine, Venezuela, the United States of America and other countries."

There are important differences between the L410 UVP and the L410VUP-E20:

The L410UVP has a three bladed prop (L410-E20 and L420 have 5 blade prop), no underwing emergency exits, 5700 kg MTOW (L410-E20 6600 kg) and M601D engines developing 725 hp (Let 410-UVPE20: M601E, 750 hp and L420: M601F, 777 hp).

The L410UVP is NOT approved for operation in South Africa and many other countries, primarily due to the fact that it does not have the underwing emergency exits. However, you willl see these aircraft operating in Africa under for instance Swazi (3D) registrations. The L410UVP is no longer in production, the current production models being the L410UVP-E20 and L420. I refer to the LET410UVP-E20.

"cursing the design flaws of this overweight designed plane"

I said the aircraft could have been built lighter, I did not say it was overweight. Like any aircraft design a compromise has to be made between a number of conflicting factors; a limitation is not a design flaw as you ineptly put it. You might recall a section in your aircraft's POH titled "Limitations" - it is unusual for the manufacturer to refer to this section as "Design Flaws"

Instead of spreading mis-information based on rumour and heresay I suggest you stick to topics you know something about. This obviously is not one of them.

[ozplane]

I don't want to divert the thread but woof's numbers on the Twotter are pretty dramatic. 25% hull losses is a bad number. Where were these losses sustained? Across the board or in Africa?

[Solid Rust Twotter]

Seen more Lets lying around Africa in kit form than Twotters.

Twotters operate in pretty harsh environments on the whole so no surprises at the mortality rate. Strips that a Let wouldn't get into are meat and drink for a Twotter. Apples and oranges as they were designed for different roles.

[Woof etc]

A quick look through the aviation-safety.net database shows that in the vast majority of accidents for both aircraft the cause of the accident is pilot error. Which is the point I'm trying to make.

[Soap Box Cowboy]

Well statistics are a wonderfull thing and so easy to manipulate.

Here are a few tid bits I found whilst researching this subject.

LET 410 design was started in 1966, with the prototype flying in 1969. But production was not started till 1971 due to problems with the initial prototype aircrafts (Excesive airframe vibration and cabin noise, Fixed on prototypes three and four). Initial versions are powered by two PT6A-27's. Then switched to Walther 601's.

Here are the versions:

L-410A 27 built and are equiped with PT6's

L-410AF 1 built supplied to Hungary, Aerial survey version with glazed nose.

L-410M 109 built first version with M601A engines producing 735 ESHP each.

L-410UVP 495 built A stretched version of the origional LET with larger wings and increased Fin and Rudder. Production ceased in 1985.

L-410UVP-E 370 built by mid 1990. Larger engine's and tip tanks fitted, plus interior modified for 19 pax instead of the orgional 15 and accomidation for two crew.

Series production reached 1000 by the end of 1990, of these 300 were for the Military.

Design work for the Twin Otter was started in 1964 with the first prototype flying in 1965 with first deliveries in 1966. By 1974 410 twin otters had been sold operating in excess of 2.3 million hours. Production was ceased in 1988 with 844 built.

Here are the versions:

CC-138 3 built. Initial version powered by two PT6A-6 engines (579 ESHP).

DHC-6-100 115 built. Short nose version with PT6A-20 engines (579 ESHP) Production completed in 1968.

DHC-6-200 115 built. Long nose version and higher gross weight option of the -100. Also available with short nose for float operations. Production completed in 1969.

DHC-6-300 613 built. Equiped with two PT6A-27 engines (652 ESHP). Increase take-off weight of 1000 lbs. Also available with a ventral baggage pod and as a water bomber. Short nose available for float version.

DHC-6-300M/MR 1 built. Designed as a military transport or Coin version with Cabin mounted machine guns and underwing hard points. Only one built and was delivered to Senegal.

DHC-6-400 0 built. Proposed developlment to meet US FAR 36 regulations, never built.

Now I agree with Solid Rust Twotter that the two aircraft were designed for totally diffrent operating enviorments. The Otter is a true bush plane, whilst the Let is a wanna be bush plane. The otter is great for the bush since you can take it anywhere, hence the increased hull loss. It operates in a riskier enviorment. But the Let beats the Otter hands down in the regular commuter market, it's faster and has a larger cabin.

Does anyone have the statistics of Hull loss per operating hour? And perhaps a breakdown of the cause of hull losses and locations. And perhaps some figures on dispatch reliability, operating cost, and some perhaps some stories from the guys who have flown the aicraft and can tell us what they think each aircraft is capable of. Or perhaps someone who has flown both and would like to offer an opinion of which they think is best.

Though getting accurate hours data for teh Let 410's may be har since some of the operators are less than truthfull :E

Seems the statistics might already be flawed :(

[Woof etc]

Both aircraft are good aircraft in their intended roles. The Twin Otter was designed from the outset as a bush aircraft. The Let is a commuter with short take off and landing capabilites and the ability to land on rough strips. UVP stands for the abbreviation of the Russian words Short Take Off and Landing.

Any aircraft is a compromise. The Twin Otter sacrifices cruise speed and comfort for lighter weight and better STOL performance.

As they say there are lies, dammed lies and statistics. However, if their was a safety issue with the LET it would be reflected in the statistics, which it is not. The inordinate proportion of hull losses in Africa points to a problem with some irresponsible operators and poorly trained pilots.

[Solid Rust Twotter]

The Twotter is a rugged, basic aeroplane with few systems so despatch reliability is very high as not much can go wrong with it.

[406pilot]

here's the story from the horse's mouth..well one of the horse's atleast...turns out they had a hydraulic problem which rendered the brakes useless but didnt declare an emergency...and landed on rwy 23 but here's the fun part..as they were struggling to slow down the tower cleared a presidential f-28 to line up on the reciprocal rwy 05 and this is when he had to make a harp turn to the left and continue the remaining of the landing roll in the grass......pretty odd huh well this is africa

keep it up there fellows,

no more 406pilot

[V1... Ooops]

OzPlane wrote: I don't want to divert the thread but woof's numbers on the Twotter are pretty dramatic. 25% hull losses is a bad number. Where were these losses sustained? Across the board or in Africa?

I posted some information about Twin Otter accidents during the period 1966 to 1997 in this discussion: http://www.pprune.org/forums/showthread.php?s=&threadid=187653

The bulk of the accidents took place in remote areas, on unimproved surfaces. So far as geographical distribution is concerned, most took place in North or South America, with Asia following close behind. The distribution may be skewed slightly as a result of under-reporting of accidents that take place in some lesser developed countries. There was a very strong correlation between operations in rugged terrain (e.g. Northern Canada, Colombia, Nepal, PNG, etc.) and the rate of accidents.

That 25% of the Twin Otters ever made have suffered a violent end is a mind-boggling statistic. Only two aircraft out of 844 were lost as a result of mechanical failure of otherwise well maintained aircraft. The vast majority of the other accidents appear to have been the result of operators (or pilots) continually pushing the limits farther and farther, until they discovered exactly where the ultimate limit was. The only good news is that the fleet-wide accident rate has dropped quite dramatically in the last 10 years.

In 1997, at the request of de Havilland, I made a presentation at a worldwide DHC-6 operator conference that looked at the accident history of the fleet, and presented recommendations to the operators to improve fleet safety. Here (in very abridged form) are the key recommendations. They assume Series 300 aircraft:

1) Review hydraulic circuit breaker policies
- over 30 accidents were caused by taxiing with CB pulled out
- old Canadian Arctic procedures are not appropriate today for most operators, especially in warm climates

2) Think very carefully before asking for reduced power takeoffs
- never from short or unimproved runways
- never in cold temperatures, or on contaminated surfaces
- the operator with the world record for TBOs (9,500 hours) never used reduced power takeoffs - every takeoff was done at max calculated power.
- a full power (50 torque) takeoff is already 'reduced', in the sense that the engine has been flat rated by DHC.

3) Have a functional autofeather system
- without question this is the most important safety feature on the plane
- if the engine fails: max power, flaps 10, 80 knots, and then fly - no rushed actions, power and prop levers all go forward, and don't touch the fuel lever.

4) Make the control lock modifications
- Implement S/B 6/508, and don’t throw out the flag

5) Get, read, and use up to date manuals & checklists
- get rid of those old pre revision 43 procedures & beliefs


Respecting pilot training issues to reduce the risk of accidents, the top recommendations were:

1) Takeoff techniques
- carefully line up the nosewheel first
- stabilize engines at 85% Ng for 5 seconds before brake release
- calculate torque for hot and high takeoffs (performance check)
- always use the full calculated power (from the AFM or torque computer), never reduced power
- after rotation, target 80 KIAS climb speed until 400 feet, then retract flaps first, and reduce power after flap retraction has completed. Excess speed is of no value to you if an engine fails, you'll just hit the ground harder. You want to climb as quickly as possible, and the best rate of climb speed for a wing with flaps 10 is 80 knots (one engine or two, it doesn't matter).

2) Landing techniques
- get props forward by 500’ AGL (VMC) or 500’ above DH/MDA (IFR)
- maintain Vref (1.3Vs) until crossing the threshold
- pull the power off completely (to the stops) when crossing the threshold

3) STOL issues
- simply using full power & following normal AFM procedures eliminates most STOL requirements
- Know when to say “NO.”
- pay attention to crosswinds, runway conditions, and pressing the weather.


Michael