NOTE 6 The following serial numbers are not eligible for airworthiness certification in the United States:
PA-31, PA-31-300, and PA-31-325:
31-7400991, 31-7512002, 31-7512026, 31-7812011, 31-7812053, 31-7812070, 31-7812080,
31-7812101, 31-7812116, 31-7812122, 31-8012045, 31-8012056, 31-8012067, 31-8012071, 31-8012083,
31-8012089, 31-8012101, 31-8012102, 31-8112037, 31-8112044, 31-8112052, 31-8112061, 31-8112072,
31-8112073, 31-8112077, 31-8212023, 31-8212024, 31-8212028, 31-8212029, 31-8212034, 31-8212036,
31-8312002, and 31-8312007.
PA-31-350:
31-7405218, 31-7405238, 31-7405485, 31-7405490, 31-7552043, 31-7552073, 31-7552076,
31-7652099, 31-7652144, 31-7852014, 31-7852042, 31-7852081, 31-7852110, 31-7852123, 31-7852133,
31-7852169, 31-7952067, 31-7952140, 31-7952184, 31-7952231, 31-8052009, 31-8052083, 31-8052145,
31-8052217, 31-8052218, 31-8052219, 31-8152067, 31-8152068, 31-8152122, 31-8152123, 31-8152144,
31-8152145, 31-8152201, 31-8152202, 31-8152203, 31-8252024, 31-8252037, 31-8252046, 31-8252058,
31-8252070, 31-8252071, 31-8252084, 31-8252085, 31-8352002, 31-8352003, and 31-8352036.
If you search some of those serials they are aircraft located in various Sth American Countries. The EMB-820c, Embraer/NIEVA built Navajo do not have certification for the USA and are not covered by the PA31 TCDS. Some of the serials may have been produced in the US for the Sth American market with similar restrictions. PA31 produced/assembled in argentina are known as PA-A-31 with similar issues as the EMB-820.