BO105 Hydraulics

[CRAN]

Chaps,

Could anyone advise, does the BO105 have a simplex hydraulic system and if so how hard to handle is it with hydraulics off?

Similarly is there a lag damper built into the blade grip, or is lag handled in the blade itself?

Many thanks,
CRAN

[GoodGrief]

She has dual hydraulics.

[wrench1]

Could anyone advise, does the BO105 have a simplex hydraulic system and if so how hard to handle is it with hydraulics off?
As mentioned above, it's a dual system with sensors to detect blockage in system 1 and switch into system 2. But it is also one of the few "closed" hydraulic systems which can lead to interesting control issues in rare instances.

Similarly is there a lag damper built into the blade grip, or is lag handled in the blade itself?
No damper. Lead/lag handled by blade bending.

[PEASACAKE]

As mentioned above, it's a dual system with sensors to detect blockage in system 1 and switch into system 2. But it is also one of the few "closed" hydraulic systems which can lead to interesting control issues in rare instances.


No damper. Lead/lag handled by blade bending.


No fond memories of maintaining these for thousands of flying hours, hydraulic problems were a consumer of many maintenance hours.

[CRAN]

Thanks guys, that makes sense.

CraN

[wrench1]

hydraulic problems were a consumer of many maintenance hours.
Can you say "microswitch"? I still have nightmares of a spring flying out while trying to fix them. But a shot of WD-40 every night before bedtime seem to keep most issues to a minimum.

But I hold no ill will to the 105. Especially after they stretched them and installed the 028 packs. Now an old CB2 with CECO systems....

Still was a fun aircraft to work on.

[SASless]

Replacing the entire hydraulic module seemed easy enough....when necessary.

[cyclic]

You can’t fly them without hydraulics, ask me how I know...

[krypton_john]

You can’t fly them without hydraulics, ask me how I know...

:-)

OK, how do you know?

[timprice]

Wow, must be fairly heavy without hydraulics', but some helicopters do seem to defy logic:8

[cyclic]

I had the infamous Hyd Block where the shuttle valve only partially moved across to the secondary system. In the new hyd pack this was thought to be impossible due to the return line that had been incorporated. The Hyd Block was caused by a faulty micro switch and neither servo was stalled. Without going into too much detail, this resulted in all the pitch being thrown off the blades in a very short period of time and the subsequent extreme nose down attitude. Pulling on the cyclic in this situation makes little difference apart from the feeling of being part of a one man team. Fortunately for me, at just the right moment, the shuttle valve moved back to the primary side and control was restored at about 140kts. Cue some aeros that Red Bull would have been proud of and I ended up making contact with the ground in what wasn’t one of my finest moments. The full comedy saga then played out over the next two days. Suffice to say, the 105 wasn’t flown off the extremely remote place that it had ended up on....not under its own steam I should say.

The hyd pack was sent to Germany and put on a test rig and the same result was produced. As far as I am aware, 5x 105s have had a similar experience, 3 were German Army at low level (not a happy result) and the other ended up inverted at about 2000’.

[GrayHorizonsHeli]

I once was certified to Overhaul those units years ago, and the micro switches to this day bring back memories I'd rather bury into history.

[wrench1]

5x 105s have had a similar experience.
Must have been a ride. If I recall there were a few others, but one hyd issue I remember is when the wrong switch over link was installed or was worn. Guy was flying at 500' when sys1 blocked due to metal contamination and during the switch over the collective dropped down. Needless to say he was pointed straight down and was a bit rattled when he got back. I member having to check the links as the ASB then AD came out and having to color code and measure them. I think after that there was a required switchover check.

[PEASACAKE]

Replacing the entire hydraulic module seemed easy enough....when necessary.

Thats if you had spare modules at £50,000 a unit.

Microswitches, can cause nightmares late at night in the feild, and yes wd40 was always in the toolbox.

[cyclic]

We reintroduced the changeover check after this incident. All was good until the chap doing my changeover check forgot to close the hydraulic access panel. Nice witness marks all the way down the side of the aircraft. They tried to kill me twice within the space of a few months so I went to fly Super Pumas instead....

[havick]

I had the infamous Hyd Block where the shuttle valve only partially moved across to the secondary system. In the new hyd pack this was thought to be impossible due to the return line that had been incorporated. The Hyd Block was caused by a faulty micro switch and neither servo was stalled. Without going into too much detail, this resulted in all the pitch being thrown off the blades in a very short period of time and the subsequent extreme nose down attitude. Pulling on the cyclic in this situation makes little difference apart from the feeling of being part of a one man team. Fortunately for me, at just the right moment, the shuttle valve moved back to the primary side and control was restored at about 140kts. Cue some aeros that Red Bull would have been proud of and I ended up making contact with the ground in what wasn’t one of my finest moments. The full comedy saga then played out over the next two days. Suffice to say, the 105 wasn’t flown off the extremely remote place that it had ended up on....not under its own steam I should say.

The hyd pack was sent to Germany and put on a test rig and the same result was produced. As far as I am aware, 5x 105s have had a similar experience, 3 were German Army at low level (not a happy result) and the other ended up inverted at about 2000’.

wow. Thanks for sharing