icing versus compressor blades

[cpt]

Does one of you ever experienced or heard about physical damages caused to engine compressor blades consecutive to ice ingestion ?

[212man]

Yes, it's one of the reasons that the location of objects protruding from the fuselage, ahead of the engine intakes, needs to be carefully considered for aircraft permitted to acrete ice (I can feel a HC vs NL thread developing;))

e.g. mirrors, probes etc

Potentially more severe is slushy ice which can collect on the intakes and then be sucked in, resulting in flame out. I know of two AS332ls that have had double engine flame outs: one over a deck in the hover, the other in the cruise at 5000 ft (he relit before they reached the surface!) I also know of a S-76 (early A model) that had a flame out on take off as ice slid off the intake into the compressor.

[Shawn Coyle]

Snow getting into the engine was a common problem on the H-500 series until a fence on the front of the transmission area was added.

I'm not sure that the ice per se is the issue - after all a lot of jets fly in known icing conditions. Certainly the rate of ice build up on the compressor blades there is very low and probably easily handled by the blades.

A good place to look for comparison would be the effect of ice on the engines of say a 727, or any of the rear-engined commuter or business jets when chunks of ice from the wing or fuselage slammed into the engine.

The real issue for helicopters is that the ice is probably much softer and wetter than that seen by a jet at high altitude, and has the tendency to come off in large chunks which put the fire out, (as mentioned earlier) as opposed to damaging the compressor blades.

[skadi]

Snow getting into the engine was a common problem on the H-500 series until a fence on the front of the transmission area was added.



Similar to the early BO 105, they experienced flameouts due to ingestion of wet snow. A shield mounted in front of the transmission and continious ignition enabled flight in falling snow.

skadi

[NickLappos]

The snow blanket kit on the engine firewall above the inlet of the S76A series is specifically to prevent the accumulation of ice/snow that threatens the engine.

All engines have internal protection for their front frames and bellmouths, but many require additional protection due to the etails of the installation.

[cpt]

Yes, engine flame-out by packs of ice, melting snow or even water is a well known incident.
I just would like to know if chuncks of solid ice ingested by an engine could damage the compressor to an extend they bend its blades outwards as a FOD would do.

Now, how this ice reaches the compressor is another question....and it highlights the difference between a de-icing an an anti-icing device.

I personally don't think, and never heard a case, where ice ingestion by a compressor ever damaged its blades, as Shawn Coyles says jet airplanes, without anti-ice barriers often undergo this occurence without damage .
But I know everything is possible in aviation unless proved else.

[excrewingbod]

Disclaimer - Non-rotorhead, but have more than a passing interest in the machines.

I found this in an article about the Bell 214ST in Helicopter World (Volume 5: Number 1: Jan-Mar 1986)

"During icing trials one of BCHL's 214s ingested a block of ice into an engine, clipping a compressor blade. The opposite blade was later clipped to balance, and that engine is still working at 106 per cent of its rated performance"

Note:BCHL = British Caledonian Helicopters.

I'm acutely aware that articles in the press may contain a bit of artistic licence and may not fully put the incident into context, however maybe someone like Speechless Two (or other ex-BCHL 214 bod) may have knowledge of the test that took place.

[NickLappos]

cpt,
I had one in heavy snow, that's how we developed the snow kit for the 76. Flamed the engine out and bent two blades badly enough to pull the engine.

[cpt]

OK, now I know it can happen....very interesting experience sharing on "pprune" !