Things you learnt in an annual that is done by a different shop!

[Tommy]

Just completed my 4th annual with my J. Glad to say that I didn't have to call my accountant for anything! I decided to go with another shop this time as my old mechanic was on a break due to family issue. Thought I will share a few things that I have learnt and hope to get some discussions going. 

1) The use of corrosion inhibiting compounds (CIC). I was a little bit shell shocked to find that the use of CICs including Corrosion X is potentially damaging to aircraft structural integrity. Australian equivalent of FAA, CASA, had conducted a research in 2012 (I am yet to read the paper in its entirety) and found "that the use of CICs on structural joints that rely on friction/clamp up force and are primarily in shear, such as aircraft lap joints, may experience a reduction in fatigue life due to the ingress of CICs on the faying surfaces of the joint. This effect is more apparent for highly loaded joints where CIC application can exacerbate relative movement within the joint. The use of CICs on certain lap joint specimens tested shifted the failure mode from sheet failure to a less desirable rivet failure mode at higher loading. Caution should be exercised in applying CIC to aircraft structural joints known to be highly loaded and/or fatigue critical. Fatigue critical joints tested in the analysis showed a reduction in fatigue life of up to half when CIC were introduced. Where a fatigue crack has been initiated, the use of CICs has been shown to increase the fatigue crack growth rate."

Is there any merit to this study? I was encouraged by my old mechanic to use it liberally to prevent corrosion. The new shop uses LPS3 instead as it doesn't work its way into the rivets and joints.

2) 14-V Hoskins power supply for strobe lights is hard to come by! Is there a drop-in replacement so I don't need to re-wire or drill new holes on the inspection panel? 

3) One of my Tempest finewires has developed a small crack on the ceramics after only ~250 hours. So it can happen! 

4) New mechanics said I should use Hobbs instead of Tach time and it can potentially save 30% of flight time (In Aus, we need to do 100-hourly or annual whichever comes first). Is that true?

5) the new shop has no less than 4 mechanics working on my J vs. 1+apprentice at the old shop. Appreantly each is expert in different system (engine, air frame, avionics, etc). I really enjoyed the efficiency but I couldn't keep up and many times things were done without my consent and participation. Hard to say "No. I don't want that to be done before I consulting MS first!" Lucky nothing was expensive!

6) I am getting one-piece belly(!) 

[Marauder]

I just finished paying for my 27th annual and I developed observations from over the years.

 

Some of the mechanics seem to gravitate to their personal pet peeve after the required items are inspected. Found some who were sloppy, some who were detailed and a few in the middle. I'm progressive on maintenance items so I usually don't get surprised on annuals. In fact some of my squawk lists are longer than the issues the shop found.

 

What irritates me? Fingerprints on everything, making my plane worse after the annual requiring a trip back and the those guys who feel they can pad a bill.

 

The ones I like; the ones who pay attention to the quality of the work they did.

 

 

Sent from my iPhone using Tapatalk Pro

 

[Yetti]

Hour meters hooked to the master spin more than the tach. If you hook the hour meeter to the gear up they may be less.

[ragedracer1977]

2 hours ago, Tommy said:

 

4) New mechanics said I should use Hobbs instead of Tach time and it can potentially save 30% of flight time (In Aus, we need to do 100-hourly or annual whichever comes first). Is that true?

 

That's the opposite of what I've always been told.  My C has only a tach.  It consistently records less time than I record chocks to chocks.  When I was in PPL training, the 172's had hobbs and tachs.  The tach ALWAYS recorded less time (we had to note both prior to and after each flight). 

[Hank]

Just now, ragedracer1977 said:

That's the opposite of what I've always been told.  My C has only a tach.  It consistently records less time than I record chocks to chocks.  When I was in PPL training, the 172's had hobbs and tachs.  The tach ALWAYS recorded less time (we had to note both prior to and after each flight). 

Yep, me too.

I do maintenance by the recording tach, and log flight time by the yoke clock, whose non-moving red hands I set either right before or after each engine start. 

[201er]

Hobbs will only save you mx time if you regularly fly >2500RPM in cruise with little ground time.

[jetdriven]

Over the last 600 hours, the Hobbs records 15-20% more time than the recording tach.  And ours is wired throirgh an oil pressure switch. You are also devaluing your engine 20% faster and you will pay this when you sell it. 

I have a Hoskins power supply for sale 

far more mooney's are totalled or require huge maintenance from corrosion than from lap joint failure due to creeping anti-corrosion  compounds. However, corrosion x is messy for years afterwards, LPs3 isn't really a lasting corrosion preventative  however Boeshield T9 and Dinitrol AV8 and AV30 work well and dry without weeping for years  

 

Edited July 16, 2017 by jetdriven

[Tommy]

So it's depending on how the Hobbs is set up. It looks like my non-functioning Hobbs is has an airspeed sensor on the wing and my mechanic said the clock is ticking only when you get 40k or above. If that's the case, then it's not difficult to see how it can save 20 to 30% of the time - particularly if you fly in and out of busy airports. 

That's what I thought as well - it's a case of catch 22. I guess my old mechanic could've got me to use the right product instead of CICs that have lubricant in it but then thelap joints might not get the protection because the proper CIC couldn't "creep" to it. 

Curious what did you replace your Hoskin with?

2 hours ago, jetdriven said:

Over the last 600 hours, the Hobbs records 15-20% more time than the recording tach.  And ours is wired throirgh an oil pressure switch. You are also devaluing your engine 20% faster and you will pay this when you sell it. 

I have a Hoskins power supply for sale 

far more mooney's are totalled or require huge maintenance from corrosion than from lap joint failure due to creeping anti-corrosion  compounds. However, corrosion x is messy for years afterwards, LPs3 isn't really a lasting corrosion preventative  however Boeshield T9 and Dinitrol AV8 and AV30 work well and dry without weeping for years  

 

 

[Bob - S50]

13 hours ago, Tommy said:

2) 14-V Hoskins power supply for strobe lights is hard to come by! Is there a drop-in replacement so I don't need to re-wire or drill new holes on the inspection panel?

When this happens on our plane I plan to replace the lights with LED units that have position, strobe, and nav all in one piece.

[jetdriven]

It's not really a catch 22. I have read that paper too but I haven't heard of bearing failure on the wing skins due to CIC compounds. However, the spars in particular are succeprible to corrosion and it's really risky to have never applied anything to prevent corrosion. 

I replaced my Hoskins with a pair of Whelen synchronized strobe boxes.  It's better but it's some money and some work to fit the boxes and connectors etc 

[jetdriven]

Those look familiar;). 

The synchronized boxes are substantially bigger. Supposedly more candlepower too but I can't tell 

[Tommy]

7 hours ago, bluehighwayflyer said:

I went with unsychronized Whelen A490TCF replacements (PN: 01-0770006-08) after also finding the OEM Hoskins increasingly difficult to maintain. Installation required a little fiddling with the connectors, and also, due to their larger size, remounting the Whelens on the larger inspection panel directly behind the smaller inspection panel on which the Hoskins were originally mounted. I then replaced the smaller inspection panels with some used ones I bought on eBay for $12 each in order to get rid of the Hoskins' mounting holes. 

All in all it was a very simple installation and now I don't have to worry about whether my strobes will work or not.

Jim

How much re wiring you need to do with Whelans?

 

[autopatch]

Just completed my 4th annual with my J. [...] Thought I will share a few things that I have learnt and hope to get some discussions going. 

 

1) The use of corrosion inhibiting compounds (CIC).

 

2) 14-V Hoskins power supply for strobe lights is hard to come by! Is there a drop-in replacement so I don't need to re-wire or drill new holes on the inspection panel? 

 

4) New mechanics said I should use Hobbs instead of Tach time and it can potentially save 30% of flight time (In Aus, we need to do 100-hourly or annual whichever comes first). Is that true?

 

 

 

#1 -- I use LPS3 and would be interested in hearing more.

 

#2 -- my strobe ballasts are mismatched and fire at different rates so I'm following responses to this too.

 

#4 -- I installed a flight Hobbs which only starts running with the pitot pressure rises above a certain level. The FAR says "flight hours" not ground hours, so yes this is true.

 

[autopatch]

Yes. Whelens triple flash and Hoskins single flash. 

 

Well, that explains that. The previous owner must have just replaced the one side. I'll just get one more Whelen then.

 

Thanks.

[steingar]

I had annuals done by others for years, and paid.  Finally found someone who would come to the hangar and do it with me.  With me watching there wasn't a whole lot wrong with the airplane all of a sudden.

[Mooney in Oz]

On 16/07/2017 at 10:17 AM, Tommy said:

Just completed my 4th annual with my J. Glad to say that I didn't have to call my accountant for anything! I decided to go with another shop this time as my old mechanic was on a break due to family issue. Thought I will share a few things that I have learnt and hope to get some discussions going. 

1) The use of corrosion inhibiting compounds (CIC). I was a little bit shell shocked to find that the use of CICs including Corrosion X is potentially damaging to aircraft structural integrity. Australian equivalent of FAA, CASA, had conducted a research in 2012 (I am yet to read the paper in its entirety) and found "that the use of CICs on structural joints that rely on friction/clamp up force and are primarily in shear, such as aircraft lap joints, may experience a reduction in fatigue life due to the ingress of CICs on the faying surfaces of the joint. This effect is more apparent for highly loaded joints where CIC application can exacerbate relative movement within the joint. The use of CICs on certain lap joint specimens tested shifted the failure mode from sheet failure to a less desirable rivet failure mode at higher loading. Caution should be exercised in applying CIC to aircraft structural joints known to be highly loaded and/or fatigue critical. Fatigue critical joints tested in the analysis showed a reduction in fatigue life of up to half when CIC were introduced. Where a fatigue crack has been initiated, the use of CICs has been shown to increase the fatigue crack growth rate."

Is there any merit to this study? I was encouraged by my old mechanic to use it liberally to prevent corrosion. The new shop uses LPS3 instead as it doesn't work its way into the rivets and joints.

2) 14-V Hoskins power supply for strobe lights is hard to come by! Is there a drop-in replacement so I don't need to re-wire or drill new holes on the inspection panel? 

3) One of my Tempest finewires has developed a small crack on the ceramics after only ~250 hours. So it can happen! 

4) New mechanics said I should use Hobbs instead of Tach time and it can potentially save 30% of flight time (In Aus, we need to do 100-hourly or annual whichever comes first). Is that true?

5) the new shop has no less than 4 mechanics working on my J vs. 1+apprentice at the old shop. Appreantly each is expert in different system (engine, air frame, avionics, etc). I really enjoyed the efficiency but I couldn't keep up and many times things were done without my consent and participation. Hard to say "No. I don't want that to be done before I consulting MS first!" Lucky nothing was expensive!

6) I am getting one-piece belly(!) 

1. My mechanic is about to use a product by the name of Cor-Ban for corrosion prevention within the wings. He is very Mooney experienced and I trust him.

2. Forget about previous generation strobes and power supplies. Save $ in the long run and fit LED nav lights and strobes.

3. Sorry to hear, glad it was caught.

4. Hobbs connected to gear switch. I assume this is what your mechanic is referring to. I have it and happy with the results. 

5. New shop for a different perspective doesn't hurt. As long as they are Mooney knowledgeable and don't rip you off.

6. One piece belly = going to Mooney heaven!

Victor

[Bob_Belville]

27 minutes ago, Mooney in Oz said:

 

6. One piece belly = going to Mooney heaven!

Victor

I have a one piece belly on my '66E. Aero Mod Inc with skid runners. It still has at least 70 screws but that's better than the original!

[Hank]

3 hours ago, Bob_Belville said:

I have a one piece belly on my '66E. Aero Mod Inc with skid runners. It still has at least 70 screws but that's better than the original!

The one piece belly on my '70C doesn't have runners, and there are 52 screws [all #10 except five little #6 arcing around the back of the nose gear doors]. I like it.

[Piloto]

I personally mostly use WD-40 for corrosion and lubrication. Boat owners buy it by the box. If you want to know anything about corrosion check with a boat owner and West Marine Stores.

https://www.westmarine.com/corrosion-inhibitor

José

[Bob_Belville]

2 hours ago, Hank said:

The one piece belly on my '70C doesn't have runners, and there are 52 screws [all #10 except five little #6 arcing around the back of the nose gear doors]. I like it.

I might exaggerate. It has happened. My screws are as yours. runners are wonderful if you do a gear up landing. The runway scraps off 1/2" or so of FG runners which are easily built back up.  

[bradp]

Hoskins are rare finds. I have a junk one if you want to try to replace capacitors.  Probably best to go with Jetdrivens.  Whelen comet flash boxes can be used in lieu.  However we had to use make a doubler with a different hole pattern that stood up on the old inspection panel mounting location with some washers and bushings to mount it properly.  

[Tommy]

14 hours ago, Piloto said:

I personally mostly use WD-40 for corrosion and lubrication. Boat owners buy it by the box. If you want to know anything about corrosion check with a boat owner and West Marine Stores.

https://www.westmarine.com/corrosion-inhibitor

José

The issue Jose, is that the study showed CICs such as WD40, Inox, and even Corrosion X that have lubricant in them will creep into joints and rivets and make them loose, reducing the structural integrity! 

It's best to use them only on the moving parts 

[Yetti]

googling navy aircraft corrosion

yields some nice bedtime reading

Best quote I have heard about marine corrosion. "Hey weren't all those offshore platforms built to withstand Hurricanes?"   "Ya when they were new.  They have been out there getting weaker for 20 years.  No one knows what they can withstand now"

[Piloto]

7 hours ago, Tommy said:

The issue Jose, is that the study showed CICs such as WD40, Inox, and even Corrosion X that have lubricant in them will creep into joints and rivets and make them loose, reducing the structural integrity! 

It's best to use them only on the moving parts 

I would rather have WD-40 in the joints and rivets than trapped moisture. Trapped moisture will lead into corrosion and decapitated rivets.

José

Edited July 18, 2017 by Piloto