Cowling Fasteners missing C172

Tom-D said:
depends upon what type fastener. The FAA has said that when special tools are required it is a complex assembly.
when the fastener is a type requiring riveting it is certainly is.
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Bell206 said:
True. But in the context of replacing a fastener or the simple repair of the a fastener receptacle for a 172 cowling, it's been my experience these type items, among others, easily fall under preventive mx per 43 Appx A(c)(12) & (26). But, as with any regulation, it is subjective to that persons interpretation and inherent skill set whether they will be comfortable performing that type of preventative mx.
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Bell206 said:
Why? As I mentioned above there are a couple prevent-mx line items that should cover those fasteners.
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The challenge for me is where to draw the line. In general tightening a screw or nut to proper torque setting is preventive maintenance. A screw walking out on the baffling sheet metal - sure. Lose cylinder nut (extreme silly example)- no.

Sometimes why a screw/nut is loose or backing out is important to understand. Should it have locktite, torque putty, proper/improper lock washer, etc? Most pilots can twist a screw driver, but do they know standards & practices to up gauge the sheet metal screw or replace the thread surface as an example?
 
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certainly, the DPE did?
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The DPE didn't. The student did and he decided to discontinue the ride because he was uncertain.
 
NordicDave said:
Should it have locktite, torque putty, proper/improper lock washer, etc? Most pilots can twist a screw driver, but do they know standards & practices to up gauge the sheet metal screw or replace the thread surface as an example?
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FYI: They are required know just as an A&P. Anytime a pilot performs any preventative maintenance they are held to the same performance standard as a mechanic per Part 43.13. So in order to perform that mx the pilot needs to dig into the books and find the answer to those questions. It's all in black and white and there for the taking. I've always found that a number of pilots sell themselves short when it comes to using their Part 43 preventative maintenance authorization. You might be surprised what you're actually capable of and legally able to perform and sign off regardless of your perceived skill level. I used to push my owner-assist customers past their comfort levels to show what the dark side looked like. And once there, most redrew that "line" at the next level.;)
 
Tom-D said:
then I would advise he contact his A&P
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And indeed, I pointed out that in my very first response. Electing NOT to go flying when the safety of flight is in question is good judgment.
 
OK, I know I'm bumping an old thread AND I know this is pedantic (I'm going to get a reputation around here...) but this raises a point that I keep running into.

When I look at the TCDS for 3A12 there are no direct references to which specific parts of the aircraft need to be attached ;), or (like in this case) attached properly (i.e. exactly how many fasteners can be missing - none?).

What I'm getting at is where is the specific reference to this missing fastener that makes it technically not airworthy? Or, say ... a fairing. Will a 172 safely fly without the fastener? Without the landing gear strut fairing? Without an oil filler door? A window? Where - specifically - are those required (yes, I realize some of those are ridiculous)? But what do I fall back on when it's a specific regulatory discussion?

The above items are not listed in the POH W&B list of Required and Optional equipment. And the 172 TCDS is very general and doesn't come close to describing the full list. 91.7 (b) leaves it open to the judgement call of "in a condition for safe flight". Is it in the official Maintenance Manual? This stuff can only be resolved by asking an A&P?

Apologies if I'm just missing something obvious. Thanks.

edit: the TCDS is a headscratcher for me. Theoretically it says you need a propeller, engine, some place to store the fuel it says it has the capacity for, and logically wings - since you need something to attach those control surfaces to that it says need a limited range of motion... :D. I would have expected a more complete description if it's supposed to be the baseline for airworthiness. ::facepalm::
 
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I ran into this same path when pre-flighting for my multi checkride in an old Apache 150. In my training we had probably never flow the thing with full gas...or if we did it was fill and fly right away....so I never noticed the problem.
Well the plane had been filled with gas, and it was dripping all over the wings....was basically a nice gentle rain of gasoline.
I said no way and cancelled the flight.
Turns out the tops of the bladders were dry rotted and cracked....did not leak when half full, only leaked when filled above some certain point. Once that was verified, the school wanted me to continue with the checkride with half fuel the following week or so.
Well I ended up taking a deep dive lesson into minimum equipment lists or lack thereof, and digging through the type cert info. This was in the days before internet so in reality is was probably just kiddie pool deep but still.... I never could find an answer either way if this was acceptable or not....and refused to fly it till they got it fixed....well I am currently a single engine rated pilot, never got my rating sadly. I'm still a little bit ticked off about it...and sometimes second guess and wonder if I shouldn't have just taken the ride as the school suggested. I'm sure that old bird continued to fly a long time like that.
 
CerroTorre said:
the TCDS is a headscratcher for me
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FYI: you’re giving the TCDS too much importance at this level in the food chain. In general terms, the TCDS is primarily a certification document. Once your aircraft is issued its airworthiness certificate (AWC) the reference shifts to Part 21, 43, and 91 per Block 6 on the AWC. For your aircraft to remain airworthy after receiving its AWC, it must continue to conform to its initial type design [or properly altered configuration] and be in a condition for safe flight.

Type design is defined in Part 21.31 and consists of the entire data package of drawings, parts listings, etc. used to conform and certify the aircraft. These aircraft parts manuals and in some cases aircraft drawings are used in the field (by you and me) as a basic reference to determine if the aircraft conforms to its type design. Alteration, repair, and 3rd party documentation would also be used for this determination if applicable. In the case of the missing fastener, the 1st place to look would be the parts manual to see if it is called out there which it is and thus is considered to be part of the type design. So technically, with that fastener missing it does not conform to its type design and is technically not airworthy. Whether you want to make it legal to fly without that fastener is outside the scope of this reply.

Keep in mind this is a very basic explanation and does not cover all topics. But as an example when I work on an aircraft the primary references I will use initially are the maintenance manual, parts manual, operators manual, AC 43.13 and any applicable alteration/repair manuals. Rarely do I look at the TCDS with most aircraft however there are some older models like a Super Cub that still list alteration and other data on the TCDS unlike newer model TCDS.
 
Brad W said:
I ran into this same path when pre-flighting for my multi checkride in an old Apache 150. In my training we had probably never flow the thing with full gas...or if we did it was fill and fly right away....so I never noticed the problem.
Well the plane had been filled with gas, and it was dripping all over the wings....was basically a nice gentle rain of gasoline.
I said no way and cancelled the flight.
Turns out the tops of the bladders were dry rotted and cracked....did not leak when half full, only leaked when filled above some certain point. Once that was verified, the school wanted me to continue with the checkride with half fuel the following week or so.
Well I ended up taking a deep dive lesson into minimum equipment lists or lack thereof, and digging through the type cert info. This was in the days before internet so in reality is was probably just kiddie pool deep but still.... I never could find an answer either way if this was acceptable or not....and refused to fly it till they got it fixed....well I am currently a single engine rated pilot, never got my rating sadly. I'm still a little bit ticked off about it...and sometimes second guess and wonder if I shouldn't have just taken the ride as the school suggested. I'm sure that old bird continued to fly a long time like that.
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I remember reading an article about a Piper Aztec that had a leaking bladder. They kept flying it. Until one day, on the ground, a spark from some old and ratty wiring for the fuel sender or nav light set it off. The wing exploded.

I wish I could find that article online. The picture was pretty stark. Leaking tanks are no joke.
 
Dan Thomas said:
I wish I could find that article online. The picture was pretty stark. Leaking tanks are no joke.
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Don't know the one you mentioned but any fuel leak has a potential. I knew the person from below who was troubleshooting a "slight" leak under the floor on a C340. Still deaf on one side I believe. And don't forget the guy who blew himself up with a cordless Makita.

explosionairplane-lafayette-regional-airport-louisana-1104-1a.jpg
 
Bell206 said:
FYI: you’re giving the TCDS too much importance at this level in the food chain. In general terms, the TCDS is primarily a certification document. Once your aircraft is issued its airworthiness certificate (AWC) the reference shifts to Part 21, 43, and 91 per Block 6 on the AWC. For your aircraft to remain airworthy after receiving its AWC, it must continue to conform to its initial type design [or properly altered configuration] and be in a condition for safe flight.

Type design is defined in Part 21.31 and consists of the entire data package of drawings, parts listings, etc. used to conform and certify the aircraft. These aircraft parts manuals and in some cases aircraft drawings are used in the field (by you and me) as a basic reference to determine if the aircraft conforms to its type design. Alteration, repair, and 3rd party documentation would also be used for this determination if applicable. In the case of the missing fastener, the 1st place to look would be the parts manual to see if it is called out there which it is and thus is considered to be part of the type design. So technically, with that fastener missing it does not conform to its type design and is technically not airworthy. Whether you want to make it legal to fly without that fastener is outside the scope of this reply.

Keep in mind this is a very basic explanation and does not cover all topics. But as an example when I work on an aircraft the primary references I will use initially are the maintenance manual, parts manual, operators manual, AC 43.13 and any applicable alteration/repair manuals. Rarely do I look at the TCDS with most aircraft however there are some older models like a Super Cub that still list alteration and other data on the TCDS unlike newer model TCDS.
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Thanks Bell206. I figured that might be the case. The TCDS seemed too general to be of much practical use (but it gets referred to so often that it makes me wonder if many folks have actually looked at it).

The 21.31 and 43.13 references are helpful and helped to click a few things into place.
 
I agree with Bells comment re the Parts Manual being required to determine proper hardware. Using incorrect fasteners can damage the receptacle / nut that could progress into a much bigger task. Too long of a screw can damage wiring, fuel lines and control cables also.

Whenever “ Cowling Security” is mentioned I will bring up fiberglass cowlings on Cherokees. There have been numerous documented failures of “ cowling separation “ ( it left the aircraft). Since this is often followed by a broken windshield, ruptured oil cooler and damage to the empennage it is often fatal.
I have shown this to several folks while traveling. When cowlings are repaired the added glass reduces the engagement of the pins at the front. It is not visually apparent but well worth verifying.

All aircraft are not created equal nor are fuel leaks. The amount of “ leakage” and location is CRITICAL and often requires the Service Manual to resolve. A “ running leak” is different than a weep or seep. Finding a fuel stain on the external bottom of a Cherokee or Mooney tank may not be cause for IMMEDIATE alarm. However; ANY leakage INSIDE the wing and you are building a bomb.

As in previous posts it seems the REGS can be interpreted to prevent a pilot properly addressing a safety issue. With cell cameras today contacting a A&P for corrective action is easy. It also becomes an issue of whether the A&P can supervise the screw installation via FaceTime or Skype. I think that’s another topic though.
 
CerroTorre said:
The TCDS seemed too general to be of much practical use
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Depends on your usage. For you as a pilot/owner there's very limited use unless you need it to comply with 91.9 or verify certain information. For an A&P it can provide required information to perform maintenance or approve an aircraft for return to service. For a DAR-T or FSDO ASI its the only document that will permit them to issue an AWC. The TCDS is an integral part of the type certificate like the type design and defines the conditions and limitations to meet certification airworthiness requirements. So basically it is written for a specific certification requirement but can also be used to comply with other non-certification issues by virtue it is an FAA approved reference. However, there is additional guidance on the use of the TCDS Notes section vs the conditions/limitations section.
 
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