EC135 LPV Approaches

[C of G]

Does anyone have any experience with LPV approaches in helicopters? I have been flying, sporadically, an EC135 with a 430W/530W setup and when I'm loading a GPS approach with LPV or LNAV/VNAV minimums, I can't get a glideslope to display in the ND. The annunciation on the GPS does say "LPV" and passed the FAWP, the CDI is showing .2nm on the head unit. There is no backup HSI or OBS with GS that I can slave to the GPS, only to a VOR/LOC freq, which ironically comes through the same GPS units.

 

 

I have been looking into TSO 146a and AC 20-130a, but just skimmed them, and I can't see any specific limitations to helicopters, but I was told by a pilot that he flew a 407 with the LPV installed and active and he got a glideslope indication. I don't think he was using a glass display, so I think it might be a switch issue somewhere on my end. He is getting a Glideslope in his glass display in the other airplanes he flies.

 

Any help or experience you guys have would be great. Thanks...

Edited April 12, 2008 by C of G

[BlackHwk27]

Are you using an HSI? If your box is displaying LPV, then it must have the WAAS in it for the glideslope indication for the approach. As long as your CDI is set to GPS and not VLOC, you should be all set. It may very well be something to do with the setup in your 430/530.

 

I may be a bit unlcear as to how your instruments are set up.

 

A good way to investigate is to download the free 430/530 trainer from http://www.garmin.com. Works great for running through the menus.

 

 

- Jeremy

[C of G]

Unfortunately I don't have an HSI that can be slaved to the GPS, only the VLOC (it is an OBS with glideslope as a back up instrument). The display I am using is an EFIS type glass display which I can get a glideslope for the ILS but none so far for the LPV. I hear a rumor that Garmin disabled it for helicopters, so I was hoping someone else might have helicopter experience with the WAAS approaches and that might help me sort it out. Anyone seen a LPV glideslope in a helicopter? Bueller?.... Bueller?... Thanks.

[Gomer Pylot]

It's my understanding that only approved operators can use the precision GPS approaches, after specific training and approval in ops specs. It may require a software update from Garmin in order to get the glideslope indication. It's certainly a software issue, but I can't give you a specific fix for it.

[C of G]

Thanks Gomer,

 

We don't have it on our ops specs yet, but that shouldn't stop us from using it pt 91, I wouldn't think. I am wondering if it is as simple as a programming issue or if helicopters are somehow restricted from the VNAV profile. I have seen, of course, the VNAV annunciations on the GPS saying I am approaching the profile, but I haven't seen a glideslope. I am still wondering if it has to do with the PFD/ND couple as opposed to a traditional HSI or OBS and slideslope. Thanks again for the responses so far, and if anyone has seen a GPS glideslope in a helicopter, I'd like to hear about it.

[BlackHwk27]

We have a 300CBI and 2 R-22s with 430s for Instrument approaches, and of thsoe 3 just one of our 22s doesn't have the WAAS. So, we shoot LPV approaches with a 22 and 300CBI. Its definitely doable. If the box is displaying LPV, then I feel you must have WAAS, otherwise it wouldn't display LNAV/VNAV, APV or just LNAV, as our 22 without the WAAS does.

 

In order to get the WAAS, we had to drop the 430 at the avionics shop for a day for them to load it.

 

Hope this helps some.

[C of G]

BH27,

 

They are definitely WAAS enabled. On start they display 430W and 530W as well as feature all of the upgrades associated with the differential GPS.

 

Just to clarify: You are getting a glideslope in the LPV approaches. Are you getting a glideslope with the non-WAAS GPS in LNAV/VNAV as well? It is my basic understanding that should be enabled as well, but I could be mistaken. Thanks again.

[spw1177]

C of G,

 

I have flown the 430W installation in a helicopter. Next time you start a GPS approach with vertical guidance, check to see if he SUSP notice comes up on the panel over the OBS button. If it does then press the OBS button to get rid of the SUSP notice and the vertical navigation should come to life.

 

Steve

[BlackHwk27]

C of G,

 

Yep, I am in fact getting glideslope on a LPV approach. On the non-WAAS box, we get no vertical guidance at all. I haven't checked lately, but I'm quite sure it will only display a LNAV approach, and not LNAV/VNAV.

 

 

spw,

 

Only thing about the SUSP mode is, that the box will sequence back to Terminal mode. If the approach is suspended, its no longer displaying LNAV or LPV or LNAV/VNAV, but instead back to TERM. Much like if you were to suspend the approach to continue holding over the FAWP.

[Superman]

We have a WAAS 430 in an R44 w/ a HSI and get a gligeslope on LPV aproaches. I may be pointing out the obvious, but make sure you have the approach activated, not just entered, its a two step process. You won't get a glideslope otherwise. We have a standard 430 in an airplane, on a gps approach, glideslope is flaged, no vertical guidance. It does get tricky flying different set-ups. I jump between 5-6 different machines, fixed and rotor and they are all set-up differently.

 

Clark

[spw1177]

BlackHwk27,

 

It was a couple weeks ago I last flew a GPS approach with the 430. But I remember the box supressing the vertical navigation portion of the approach until I pressed the OBS button to extinguish the 'SUSP' indication on the box.

 

spw1177

 

C of G,

 

Yep, I am in fact getting glideslope on a LPV approach. On the non-WAAS box, we get no vertical guidance at all. I haven't checked lately, but I'm quite sure it will only display a LNAV approach, and not LNAV/VNAV.

 

 

spw,

 

Only thing about the SUSP mode is, that the box will sequence back to Terminal mode. If the approach is suspended, its no longer displaying LNAV or LPV or LNAV/VNAV, but instead back to TERM. Much like if you were to suspend the approach to continue holding over the FAWP.

Edited April 17, 2008 by spw1177

[C of G]

C of G,

 

I have flown the 430W installation in a helicopter. Next time you start a GPS approach with vertical guidance, check to see if he SUSP notice comes up on the panel over the OBS button. If it does then press the OBS button to get rid of the SUSP notice and the vertical navigation should come to life.

 

Steve

 

 

spw1177,

 

Thanks, I'll look into that. I'll report back if it works or not. Thanks a alot.