Prop Strike due to partial gear collapse

[Urs_Wildermuth]

This is what mine looks like, not quite from straight but as good as I could take the pic.

We tried extensively on jacks the other day, as far as I can tell the system works well enough. But one has to be diligent to really get the feed back when the pin clicks.

[Urs_Wildermuth]

2 hours ago, bluehighwayflyer said:

That down lock block is severely worn and is the source of your problems, Urs.  You need to replace it.  

Ok, so where can I source one? Or better both of them.

[hammdo]

@Sabremech was instrumental in the manufacturing of those blocks. He may have some guidance if Lazar is out of stock. 

Also, make sure the Johnson Bar is straight - that can cause those blocks to wear out too... 

-Don 

[carusoam]

Urs,

To see how common this issue is….

See this thread.

From the mock-up drawing, you can see the round hole, and no ledge…

It is such a wide spread challenge… I threw in my lunch money that day to help defray the cost of getting a drawing made… My M20R doesn’t have lock blocks…   

Yours is really worn.

-a-

 

[hammdo]

Nice info on the blocks...

https://www.knr-inc.com/shoptalk-articles/25-shoptalk/41-200305-manual-gear-mooneys

-Don

[bradp]

Almost never a good idea to take a damaged aircraft back into the air purposefully. 
 

If it’s a gut reaction to do something less safe in a reaction to an emergency, probably ripe to be trained away.  That’s the only way to avoid gut reactions.  Training and planning.  

[ilovecornfields]

5 hours ago, bradp said:

Almost never a good idea to take a damaged aircraft back into the air purposefully. 
 

If it’s a gut reaction to do something less safe in a reaction to an emergency, probably ripe to be trained away.  That’s the only way to avoid gut reactions.  Training and planning.  

“Now you’re looking at the man that formerly held a pilots license”

Seems like a good example of “better to be lucky than good.”

Edited September 17, 2021 by ilovecornfields

[47U]

On 9/6/2021 at 1:42 PM, DXB said:

The lever inside the lock block that turns on the green light also silences the gear warning horn circuit.That lever is depressed by the top of the handle a tad bit before the the locking pin actually engages. That leaves room for the green light to be on and the horn to be silenced but the gear not to be fully locked down.    I’m sure that’s how it is on my setup - There should be room for adjustment internal to that switch.

Apologies that I’m a late to this discussion.

The gear warning switch (lever) should be adjusted so that the gear down green light doesn’t come on until after the handle is seated above the lock pin.  My learning event occurred when I had only about 20 hrs in my C… I lowered the gear on downwind, but was a little high turning base.  I pulled the throttle out far enough that the gear warning horn sounded.  It was wifey’s first Mooney ride and she was not impressed.  I had failed to verify the light turned green when I put the gear down.  My gear-lowering technique was not fully developed.  I hadn’t purposefully seated the handle up into the block.  The ugly scene is burned into long term memory.

With further practice, I found that with the handle seated all the way up into the down lock block and green light on, if I pull down on the handle (without pushing the thumb catch) that the unlock light will come on.  The handle only moves an eighth inch, if that much.  

Now when I lower the gear I verbally call out the green light and I know the gear is locked down.  I make additional call outs for the green light on base and final.  

[A64Pilot]

On 9/17/2021 at 6:49 AM, bradp said:

Almost never a good idea to take a damaged aircraft back into the air purposefully. 
 

If it’s a gut reaction to do something less safe in a reaction to an emergency, probably ripe to be trained away.  That’s the only way to avoid gut reactions.  Training and planning.  

Somethings you just can’t make up, without video evidence, I wouldn’t have believed it.

[Hank]

5 hours ago, A64Pilot said:

Somethings you just can’t make up, without video evidence, I wouldn’t have believed it.

"Truth is stranger than fiction, because fiction has to make sense."

[Urs_Wildermuth]

We have a new problem. After 9 months waiting time, the new propeller has finally be delivered, a brand new Hartzell HC-C3YR-1RF/F7282 3 blade prop.

Why 3 blade? When we asked, we were not given any lead time at all for a 2 blade prop (out of production) and a 6 month waiting time for a 3 blade. Well, we ASSUMED it would be quieter and getting us a better noise certificate, so we would pay less punitive noise charges.

While doing a testflight last week, we found that the new prop is quite a lot quieter. TO the naked ear that is.

The shock came when we were issued the noise certificate, which puts it in the highest noise class available with over 85db take off noise under ICAO Annex 16, chapter 10. This is catastrophic and a no go, as it prohibits training and makes the plane subject to massive noise fees in Switzerland and other nearby places. The 2 blade was certified under chapter 6 and had somewhere like 72 db and therefore was a much lower noise class.

My question here is: Is there anyone in Germany or otherwise in Europe who has this combination of a M20C with the HC-C3YR-1RF/F7282 prop and who has a noise certificate having an actual measurement behind it? What I hear is that most people assume that the 85DB value is not a measurement but an estimate.

We need urgent help on this because quite likely we are sitting on a prop we can't use and face another total loss of a flying season.

Thanks a bunch.

 

[takair]

2 hours ago, Urs_Wildermuth said:

We have a new problem. After 9 months waiting time, the new propeller has finally be delivered, a brand new Hartzell HC-C3YR-1RF/F7282 3 blade prop.

Why 3 blade? When we asked, we were not given any lead time at all for a 2 blade prop (out of production) and a 6 month waiting time for a 3 blade. Well, we ASSUMED it would be quieter and getting us a better noise certificate, so we would pay less punitive noise charges.

While doing a testflight last week, we found that the new prop is quite a lot quieter. TO the naked ear that is.

The shock came when we were issued the noise certificate, which puts it in the highest noise class available with over 85db take off noise under ICAO Annex 16, chapter 10. This is catastrophic and a no go, as it prohibits training and makes the plane subject to massive noise fees in Switzerland and other nearby places. The 2 blade was certified under chapter 6 and had somewhere like 72 db and therefore was a much lower noise class.

My question here is: Is there anyone in Germany or otherwise in Europe who has this combination of a M20C with the HC-C3YR-1RF/F7282 prop and who has a noise certificate having an actual measurement behind it? What I hear is that most people assume that the 85DB value is not a measurement but an estimate.

We need urgent help on this because quite likely we are sitting on a prop we can't use and face another total loss of a flying season.

Thanks a bunch.

 

Did you ever have the old levels measured?  Is it possible that the flame tubes in your muffler are deteriorated and contributing to the higher noise levels? 

[brndiar]

Hi,

The same problem. I Started a Thread, back in 2020, your reply is in that Thread (Screenshoot below).

75 dBA was a result that was achived with a different noice mesuring system (old one).

From Hartzell I got a link to EASA  database

https://www.easa.europa.eu/domains/environment/easa-certification-noise-levels

and explanation:

"Whatever the reason, for the listings in the EASA noise level archives, you can bet that we had nothing to do with it. Here’s what I can tell you about it

Prior to 1988 noise was measured at 1000’ AGL (overflight). In FAA speak, this was FAR 36, Appendix G. EASA, or more specifically the Authorities that preceded EASA called in ICAO Annex 16, Chapter 6.

After 1988 both organizations changed to a noise measuring system that took take-off and climb performance into account. The better a plane climbed, the higher it would be at 8200’ from where the airplane started rolling, and the microphone is set up. This Take-off method is called FAR 36, appendix G, or ICAO Annex 16, Chapter 10.

I can tell you that Hartzell never tested a M20C with any prop on it for the FAA or EASA. Both of these prop TC/STC’s were validated in Europe well before EASA was established. Hence they were grand-fathered in without any noise testing on our part.

The note that EASA has pertaining to the three blade entry is “”9/24/201 Engine designation revised”.  

Looking at the numbers themselves, the Chapter 6 numbers are on props that were TC’ed. Maybe these numbers came from Mooney from the TC process? I can only guess. The 7282 three blade is approved on an older STC. In 2010 we added eligibility for the Powerflow exhaust to the STC. The only thing I can think of is that when Powerflow applied to validate their STC it must have initiated some noise discussion. If you will note, 85.5 dB(a) is the maximum allowable under Chapter 10. That seems like allot for un untested unit that is the same diameter as the two blade??

So, to get to the bottom of your questions, The props are the same diameter. They should be about the same noise-wise, except the 3 blade climbs better (CHAPTER 10). The numbers in the archive compare two 74” props at the same RPM, using two different methods, one of which may be considerably closer to the mic, and the Chapter 10 listing is as high as it can be to pass. It seems almost arbitrary?? The three blade certainly is not 10 dB(a) louder than the two blade."

lg,

m

 

 

Edited July 11, 2022 by brndiar

[chriscalandro]

I have a set of lock blocks to sell. 

[ilovecornfields]

I don’t know anything about the European regulations, but that sounds horrible.

Are you allowed to take off at a lower RPM for noise abatement or is the limitation based on the prop/airframe combination and not the actual amount of noise you produce on takeoff?

I’ve sometimes taken off at 2550 RPM instead of 2700 in my Ovation at airports that are long on runways and short on noise tolerance.

[Sue Bon]

17 minutes ago, ilovecornfields said:

I don’t know anything about the European regulations, but that sounds horrible.

Are you allowed to take off at a lower RPM for noise abatement or is the limitation based on the prop/airframe combination and not the actual amount of noise you produce on takeoff?

I’ve sometimes taken off at 2550 RPM instead of 2700 in my Ovation at airports that are long on runways and short on noise tolerance.

No, unfortunately not. We are given a noise certification and that is it. All noise fees are based on the certification. I have B, which is the second worst. 

[Urs_Wildermuth]

Well, for the moment we are back to "B" which is not the improvement we originally looked for with the 3 blade over 2 blade but it is a workable solution for the moment.

 

[Shadrach]

21 hours ago, Sue Bon said:

No, unfortunately not. We are given a noise certification and that is it. All noise fees are based on the certification. I have B, which is the second worst. 

What does that translate to in actual cost? Do you pay for flight or annually?  We have a V tail Bo and a C185 on the field that I am pretty sure have supersonic tip speeds on take off. They both sound similar and the noise is considerably louder and sharper (almost like a constant rifle crack) than other aircraft.  Is noticeable for sure, but has faded to a mild drone with in a minute or two.  I could see how it might annoy nearby homeowners if those planes flew circuits all day every day, but that is not the case.

[Sue Bon]

4 hours ago, Shadrach said:

What does that translate to in actual cost? Do you pay for flight or annually?  We have a V tail Bo and a C185 on the field that I am pretty sure have supersonic tip speeds on take off. They both sound similar and the noise is considerably louder and sharper (almost like a constant rifle crack) than other aircraft.  Is noticeable for sure, but has faded to a mild drone with in a minute or two.  I could see how it might annoy nearby homeowners if those planes flew circuits all day every day, but that is not the case.

Noise fees are paid by movement (start and landing) and it depends on the airport. If I fly to St. Gallen/Altenrhein (LSZR) it costs me over CHF 120.- mostly due to noise fees. At my home airport it's CHF 5.55 per movement, so CHF 11.10 for one flight.

And the comment above about it being arbitrary is absolutely correct. As I said, my 1977 J with 2 blade prop has a noise rating of B, the second loudest. The 1979 J that I rented while my plane was grounded has a three blade prop and has the quietest rating, a D. So I really don't understand how poor Urs went to an A rating after getting a three-blade prop.

FYI, I found a C185 on the Swiss Aircraft Registry that has a C rating, so better than mine. I couldn't find a V-Tail Bonanza.

[Shadrach]

26 minutes ago, Sue Bon said:

Noise fees are paid by movement (start and landing) and it depends on the airport. If I fly to St. Gallen/Altenrhein (LSZR) it costs me over CHF 120.- mostly due to noise fees. At my home airport it's CHF 5.55 per movement, so CHF 11.10 for one flight.

And the comment above about it being arbitrary is absolutely correct. As I said, my 1977 J with 2 blade prop has a noise rating of B, the second loudest. The 1979 J that I rented while my plane was grounded has a three blade prop and has the quietest rating, a D. So I really don't understand how poor Urs went to an A rating after getting a three-blade prop.

FYI, I found a C185 on the Swiss Aircraft Registry that has a C rating, so better than mine. I couldn't find a V-Tail Bonanza.

Ugh...That is an unfortunate state of affairs. I am sorry. It puts things in perspective. Local pilots in my area are complaining about current fuel pricing. I just paid 1.71L at a small strip near my base, which is about the least expensive in the area.  I tell them that it could be much worse and probably will be soon.