14 CFR §194.255

1. (a)Notwithstanding § 61.64(f) of this chapter, a person who holds a powered-lift category, instrument-powered-lift rating, and powered-lift type rating and seeks an additional type rating for a powered-lift with a single functioning control and a single pilot station in accordance with §§ 61.63(d) and 61.64(a) of this chapter, and does not meet requirements of § 61.64(e), will receive a limitation on the certificate restricting the person operating the powered-lift type from carrying any person or property on the aircraft, other than necessary for the purpose of paragraph (b) of this section.
2. (b)The limitation described in paragraph (a) of this section may be removed from the rating if the person complies with the following:
   1. (1)Performs 25 hours of flight time in the type of powered-lift for which the limitation applies under the observation of a fully rated pilot without limitations for the aircraft, maintaining full communication with the observing pilot,
   2. (2)Logs each flight and the observing pilot attests in writing to each flight, and
   3. (3)Presents evidence of the supervised operating experience to any examiner or Flight Standards office to have the limitation removed.
3. (c)The observing pilot must have unobstructed visual sight of the controls and instrumentation.