Tesla is suing a former supplier over a contractual disagreement over the Model X's crazy-complicated (and just crazy) Falcon Wing doors.

Hoerbiger is a Swiss supplier of hydraulic systems for things like trunk lids and lift gates, and had a partnership with Tesla from February 2014 to May 2015 when the deal was terminated. Though the relationship never entered the production phase, the development products that Hoerbiger designed failed to meet Tesla's expectations.

In the lawsuit, Tesla says the doors were prone to overheating (making the doors inoperable), did not open with speed or symmetry, and they "sagged" beyond tolerance levels. Tesla's lawyers sum it up in the initial filing:

After enduring Hoerbiger's defects and false assurances, paying for a year of fruitless development work, and having incurred significant costs as a result of Hoerbiger's failed promises, Tesla decided to pursue an alternative supplier and engineering design for the actuation system of the Model X Falcon Wing doors.

The lawsuit alleges that the supplier continued to make demands of Tesla for damages and finances, and Tesla is asking in the lawsuit for a judge to agree that Tesla is not in breach of its contractual obligations and that Tesla owes nothing to Hoerbiger, and for damages related for negligent misrepresentation based on the promises regarding the Falcon Wing door.

Ultimately, this lawsuit isn't about customers, but it does show the problems Tesla has had with the complicated (and perhaps unnecessary) Falcon Wing door on the Model X. The company still doesn't appear to be shipping the vehicle in its desired volumes and that may be related to production problems on some of the fancier features of the Model X like the Falcon Wing doors and the rear seats.