Pre-Cover Inspection Requirements. 750 STOL, Canada.

by Klaus Gebert

Mar 12

Canadian Pre-Cover Inspection for 750 STOL. Hi all. By now I have bin searching for hours on the MD-RA  web site about how far to build the different component for a Zenith 750 for the pre-cover inspections without success. The instructions states that the parts are not to be covered. How did you accomplice this a with a monocoque designed airplane where the skin/cover also has to function as loadbearing structure? If anyone is able and willing to point me in the right direction, I would appreciate it. Thanks, Klaus.

  • John Montgomery

    Good  topic!! When building our club 750 Cruzer components we just needed to provide access for inspection.  So for parts like the horizontal stab and wings we assembled everything and did not rivet stabilizer and wing top skins.  Top skins were drilled but only cleco'd until the pre-cover inspect was done.  Only then were they closed up and riveted.  It helped that our inspector was located near us so we did not have to pay for travel or try to get everything done in one go...  I'd love to see general planning and inspection preparation advice from  builders located in a more remote area.  I am really curious where using a modern endoscope inspection camera is ok.

    Mar 12

  • Klaus Gebert

    Thank you John. How did you handel the situation with the Ruder, Flaperons? In my case there are also the Slats. I hade the same thought about a endoscope with camera. I am living and building 30km. North of Prince George and the inspector is in Vancouver. So I realy like to get it right dhe first time. Klaus.

    Mar 12

  • John Montgomery

    Just for fun I used AI to dig up info on these questions for me just now.  Very useful for gathering and summarizing the info no obvious on the MDRA web pages.  I paste what it said here:

    Core Rule: No Permanent Closure
    The most critical guideline is that nothing enclosed should be permanently riveted or closed unless the internal areas remain visually accessible to the inspector. If you close a component (such as a wing or fuselage section) before the inspection, the inspector can legally require you to "unrivet" or remove skins to reveal the internal workmanship. 
    Pre-Cover Inspection Guidelines
    Guidelines on preparation are detailed in the MD-RA Construction Procedure and specifically within the C20E Inspection Procedures: 
    • Materials & Samples: You must have samples of your work available for the inspector to test, including samples of glue, welding, composite layups, or riveted joints.
    • Documentation: Before the inspection, you must have submitted a Letter of Intent (Form C01E) and received a "Reply to Letter of Intent" (Form C09E) from the MD-RA office.
    • Progress Level: The project should be "as far advanced as possible" without closing any structures.
    • Component Flexibility: You can choose to have a single pre-cover inspection for the whole aircraft or separate inspections for major components (fuselage, wings, etc.) as they are completed. 
      www.md-ra.comwww.md-ra.com +1
    Specific "Dos and Don'ts"
    What You CAN Do  What You CANNOT Do
    Assemble components using temporary fasteners (like Clecos). Permanently close any area that will be inaccessible later.
    Proceed with construction once you have received your C09E reply. Apply fabric, paint, or final skins that hide internal structure.
    Prepare all paperwork, including your builder's log and construction photos. Skip the pre-cover and go straight to final inspection (this is prohibited for homebuilts).
    ----->
    Will my MDRA inspector accept using something like an endoscope camera if I have riveted closed a component like my rudder?
    In most cases, 
    an MD-RA inspector will not accept an endoscope or borescope as a substitute for a physical pre-cover inspection of a closed component like a rudder. 
    The MD-RA's primary mandate is to verify internal workmanship—specifically the "shop heads" of rivets, internal corrosion protection, and proper assembly—before they are hidden. 
    Why an Endoscope is Likely to be Rejected
    • Regulatory Policy: MD-RA guidance generally mandates that all internal areas must be visually accessible to the inspector's own eyes (often aided only by a mirror and flashlight).
    • Detailed Verification: Inspectors check every single fastener for proper formation, "smoking" (signs of movement), or defects. An endoscope often lacks the resolution or field of view to allow an inspector to confidently sign off on the entire internal structure.
    • Legal Standing: If a component is closed before inspection, the inspector has the legal authority to require you to "un-rivet" or remove skins to reveal the work. 
    Exceptions and Nuance
    • Specific Designs: Some components (like certain Van's RV rudders) have large enough lightening holes that an inspector can see everything through them with a mirror and light. In these cases, the component is technically "closed" but still "accessible".
    • Inspector Discretion: While the official "song and dance" from the MD-RA office is that everything must be open, individual inspectors have some discretion. If you have already riveted the rudder, call your assigned inspector immediately to discuss the situation before doing anything else.
    • Factory-Closed Parts: Only parts closed by the kit manufacturer (and noted on the kit's approved parts list) are exempt from pre-cover inspection. 
    Recommended Course of Action
    1. Do not rivet anything else closed. Use temporary fasteners like Clecos to hold everything together until the inspector arrives.
    2. Contact your inspector. Explain the situation if required about a closed component.. They may ask for detailed high-resolution photos taken during construction, or they may tell you exactly which rivets need to be drilled out to provide a "peek" inside.
    3. Prepare to drill. If the inspector cannot see the shop heads of critical internal rivets, expect to drill out enough rivets to at least partially open the skin for a visual check. 

    Mar 12