Jet turbine reliability

At 20:47 06 July 2015, Ramy wrote:
There was a recent landout of a brand new JS1 in the middle of nowhere
near
Hobbs during the contest due to jet failure. Multiple attempts were made
to
start it.
So much for jet reliability. Apparently can't trust them either.
I heard of at least 3 landouts of motorgliders recently.
Hopefully electric motors will be more reliable.

Ramy

It would be interesting to know why that jet didn't start and also whether

it had been run in the air or on the ground before the task that day.
The
jet glider pilots I have spoken to don't seem to routinely do test runs but
I
can imagine simple problems that could be found - e.g. airlock in the fuel

line after trailering. The JS1 jet overhaul interval is going to be based
on
number of starts rather than hours so perhaps that is a disincentive. In
22 years I never intentionally took a 2 stroke turbo cross-country without

doing a test run before starting the task. I occasionally uncovered
starting
problems that were easily fixed back on the ground. Any time the turbo
didn't start there was always a straightforward reason for it. At least
the
jets can be started on the ground for a few seconds so a problem could be
found found before taking a launch rather than afterwards.

John Galloway

On Monday, July 6, 2015 at 1:47:38 PM UTC-7, Ramy wrote:
There was a recent landout of a brand new JS1 in the middle of nowhere near Hobbs during the contest due to jet failure. Multiple attempts were made to start it.
So much for jet reliability. Apparently can't trust them either.
I heard of at least 3 landouts of motorgliders recently.
Hopefully electric motors will be more reliable.

Ramy

HpH 304 Shark jet sustainer owners have reported a very reliable jet start. HpH uses a TBS J40 Engine.

Sean Franke

I don't have more details except that the jet engine was later removed and sent for repair.

Ramy

On Monday, July 6, 2015 at 1:47:38 PM UTC-7, Ramy wrote:
There was a recent landout of a brand new JS1 in the middle of nowhere near Hobbs during the contest due to jet failure. Multiple attempts were made to start it.
So much for jet reliability. Apparently can't trust them either.
I heard of at least 3 landouts of motorgliders recently.
Hopefully electric motors will be more reliable.

Ramy

May be a good thing it didn't light after multiple start attempts.. it's usually the condition under which you'll get a wet start. May not be a big deal in this configuration but depends how much residual fuel was there.

On Monday, July 6, 2015 at 5:21:03 PM UTC-5, Ramy wrote:
I don't have more details except that the jet engine was later removed and sent for repair.

Ramy

The failure to start was not at Hobbs, but flying from Moriarty before going to Hobbs for the contest. The engine removal happened at Hobbs after troubleshooting by swapping parts from one plane to another.

Steve Leonard

At 14:34 07 July 2015, Steve Leonard wrote:
On Monday, July 6, 2015 at 5:21:03 PM UTC-5, Ramy wrote:
I don't have more details except that the jet engine was later
removed
and sent for repair.

Ramy

The failure to start was not at Hobbs, but flying from Moriarty before
going to Hobbs for the contest. The engine removal happened at Hobbs
after
troubleshooting by swapping parts from one plane to another.

Steve Leonard


Steve, was a diagnosis made as a result of the troubleshooting?

John Galloway

On Tuesday, July 7, 2015 at 11:45:05 AM UTC-5, John Galloway wrote:
At 14:34 07 July 2015, Steve Leonard wrote:
On Monday, July 6, 2015 at 5:21:03 PM UTC-5, Ramy wrote:
I don't have more details except that the jet engine was later
removed
and sent for repair.

Ramy

The failure to start was not at Hobbs, but flying from Moriarty before
going to Hobbs for the contest. The engine removal happened at Hobbs
after
troubleshooting by swapping parts from one plane to another.

Steve Leonard


Steve, was a diagnosis made as a result of the troubleshooting?

John Galloway

You would need to talk with Bill Gawthrop and Dave Coggins about what was determined.

Steve

On Monday, July 6, 2015 at 1:47:38 PM UTC-7, Ramy wrote:
There was a recent landout of a brand new JS1 in the middle of nowhere near Hobbs during the contest due to jet failure. Multiple attempts were made to start it.
So much for jet reliability. Apparently can't trust them either.
I heard of at least 3 landouts of motorgliders recently.
Hopefully electric motors will be more reliable.

Ramy

I am interested in knowing which type of motorgliders and was a start attempted vs landing because there was insufficient altitude for a restart. My experience is that engine restart is very reliable because you have the benefit of windmilling to spin the prop faster (I know nothing about the jets). Most failures to start are the result of pilot error (myself included). But everything mechanical is subject to failure (that includes towplanes!).

Tom

On Tuesday, July 7, 2015 at 4:46:43 PM UTC-4, 2G wrote:
On Monday, July 6, 2015 at 1:47:38 PM UTC-7, Ramy wrote:
There was a recent landout of a brand new JS1 in the middle of nowhere near Hobbs during the contest due to jet failure. Multiple attempts were made to start it.
So much for jet reliability. Apparently can't trust them either.
I heard of at least 3 landouts of motorgliders recently.
Hopefully electric motors will be more reliable.

Ramy

I am interested in knowing which type of motorgliders and was a start attempted vs landing because there was insufficient altitude for a restart. My experience is that engine restart is very reliable because you have the benefit of windmilling to spin the prop faster (I know nothing about the jets). Most failures to start are the result of pilot error (myself included). But everything mechanical is subject to failure (that includes towplanes!).

Tom

It's a frikkin jet..... not much "windmilling" going on within VNE of the glider........

Guess you didn't read most of the thread...... ;-)

And.......they are still derivatives of model engines made by model engine manufacturers. We're not talking GE or Pratt & Whitney here