Twin loss of control - UK

Ted Smith must have had an aversion towards hydraulic pumps, because this is the second twin of his design in my ownership certified without that redundancy. Thankfully, the Aerostar has an STC to put an electrically driven auxiliary hydraulic pump in and I’m rather happy it came with that. It’s a bloody stupid design – they have redundancy in most things that are not nearly as important as the hydraulics and I can’t help but wonder – why? Cue an engine failure on takeoff in any of these on the bloody gear comes out! Nevermind trying to eke out a climb. I’d much rather have an extra hydraulic pump than an extra alternator.

And tying into another post you did Peter on another subject: I hope with the revisions of FAR 23 that solutions that actually improve safety very considerably will find a way to get approved in the future. I looked into putting a second hydraulic pump on the right engine on the old Commander, but there was no way of doing so legally. Even though there was an empty space on the engine at the accessory case. Nope, couldn’t be done. Looked into taking an STC electric aux hydraulic and tying that in, but that would have to be STC’d at great cost, so no.

They’d rather we kill ourselves than have non compliance. You have been assimilated.

Can one install a second hydraulic pump, onto the other engine?

Well, I have had different stories, the most recent of which is “no”.

This is perhaps more an argument for not flying that plane rather than manual flaps…

and walk home from the middle of the desert?

thanks but no thanks

“Properly trained” is one thing … STAYING trained the other, and the more important one. I WAS properly trained for multienngine aircraft amd at the end of the course (Seneva V) i was very good at it. But 5 years later I was UNSAFE. And that’s how it goes many times, with PPL. IFR, Aerobatics. multiengine …

Piper Aztec flaps are hydraulic. However, most Aztecs only have one engine driven hydraulic pump, so you have to know which engine, ‘cause if that one quits, you’ll have to pump them up (along with the gear) while you configure the plane for single engine climb out – it gets busy for a minute in the cockpit.

Just to be clear, while this is quite true (and the weakest link in the Aztec’s safety chain, which is generally very strong), it has nothing to do with Asymmetry. In the Aztec, the two flaps are connected by a very tough torque tube, which had to be replaced by AD recently, so they are all young.

Because of the single pump (which is on the left engine, making the left doubly critical) I always rotate at blue line and whip the gear up as soon as the wheels are off the ground. That means that if the left engine fails, even the residual turning, before it feathers, is likely to get the gear up, or most of the way up. Also, no flap on take-off for the same reason.

In the go around from very low (I am not talking about a Missed Approach go-around, where you have 200’ in hand, but a visual go around from 10’) my technique is to apply only enough power to fly level along the runway, get the gear and flap up, then apply climb power. All of this to manage the risk of losing the left engine in a high power, low speed, flaps and gear dirty scenario.

These are the kinds of calculations you have to make when working with risk on light twins.

But if Bloomer won’t fly with me, I am sure I can find other people

Twins are safe if you are properly trained. With that said, I owned a 310Q for four years and the 310 (as a make/model) can be a bit tricky. The Seneca is a puppy compared to the 310. The key is speed. I never operated from short runways so I could always make flaps up takeoffs and I would rapidly accelerate to Vyse + 20 asap. Approach was same idea…Vyse +20 until runway assured.

Did they not put the screws back in?

Sometimes screws come loose by themselves… I had a scary moment when I collected “my” Citation Encore from a scheduled maintenance event this spring (and our aircraft are really well maintained!). It has two sections of flap on each wing and each section is operated by bellcranks and pushrods attached to both sides like in this drawing here (the closest Google image search could provide):

A mechanic from the maintenance company showed me that one of the bolts connecting the pushrod to the bellcrank of an outer flap section had fallen out, nowhere to be found. Which means the the flap was only connected at one side instead of both. Invisible during pre-flight inspections, the mechanism is inside the wing and only accessible after removing several inspection panels. Also we can not really move the flaps on the ground because they are operated hydraulically and hydraulics is only available with the engines running. But what it dangerous? I don’t know. Flaps are only moved one stage at a time and if an asymmetry is felt, you put them back to the last position. But still, during a low-level go around at low speed/poor control authority this would certainly not reduce the workload.

Never got a full and proper explanation of what happened. I was young and daft and let them off the hook and didn’t file an MOR