The addendum clearly states that Major Structural Inspections (MSIs) are part of Chapter 4 -- Airworthiness Limitations and are therefore required at 2000 hours or 12 years, whichever comes first, with a maximum tolerance of _+ 2.5% (about 3.5 months) for N-registered aircraft.
A Major Structural Inspection (MSI) is required: at 2000 hours since new or 12 years (that which comes first) and at 2000 hours intervals or 12 years (that which comes first) after the initial MSI. Maximum tolerance is ± 2.5% OR If MÄM 40-394 or MÄM 40-398 is installed: at 6000 hours since new and every 4000 hours intervals or 12 years, whichever comes first. Maximum tolerance is ± 2.5%
Heretofore, MSIs have been listed in Chapter 5, which is NOT mandatory for N-registered aircraft. I called Diamond Canada and spoke to the head customer representative, Will. In response to my inquiries Diamond had a meeting to discuss. With his permission, this is their position.
Diamond's position that is the following language in Chapter 4 means that even though MSIs are contained in Chapter 5, they are MANDATORY AS CHAPTER 4 Airworthiness limitations. Prior to the addendum, the relevant section of Chapter 4 stated:
(2) Life Time Limit / Structure Checks%
There is no structural life limit.%
Note: The DA 40 has been designed and tested under a 'damage tolerant structure'% philosophy. Therefore the structural inspections given in Chapter 05 cover all required structure checks.
See Chapter 4, page 5 in http://support.diamond-air.at/fileadmin ... mplete.pdf at page
Diamond's view is that the language in bold has already required MSIs as Chapter 4 airworthiness limitations and that the addendum only clarifies that. Diamond further believes that the extension to 6000 hours if "MÄM 40-394 or MÄM 40-398 is installed" does NOT change the fact that an MSI is required at 12 years, if that comes first. (Despite the fact that the sentence structure and wording used are completely different from that used for the 2000 hour limit.)
I would be interested in what you all think. Thanks. Bernie