Until you are instrument rated, you may NOT act as PIC on any flight being conducted under an IFR flight plan. You may not file an IFR flight plan until you are an instrument rated pilot. There are no exceptions to 61.3 for check rides. 350 is in error to suggest otherwise.
61.3(e) is quite specific that no one may act as PIC under IFR unless they hold an instrument rating. Since you are not yet rated at the point you are taking the practical you may not file the flight plan, nor may you act as PIC if the flight is being conductged under an IFR flight plan. The DE would have to do the filing and agree to act as PIC for that portion of the flight for it to be legal. If the IFR flight plan is cancelled, you may then act as PIC.
Now, as for the other responses indicating DEs logged PIC time in their logbooks when signing them, there are explanations backed by the FAR. Let's take a look.
1. PPC - first of all, *someone* has to be acting as PIC on board every plane. 61.51 allows students to log PIC time and to act as PIC during solo flight. The prohibition for student pilots is that they can't carry passengers. However, 61.47(c) takes care of that by waiving this requirement for the check ride. Thus, 61.51(e) allows you to log PIC time. You are acting as PIC under the regulations governing the flight.
2. Commercial and Instrument - again, 61.51(e)(1)(i) allows you to log PIC time when you are sole manipulator of the controls of an aircraft for which you're rated. As a commercial pilot or a pilot seeking an IR, you are typically already at least a private pilot, so there's no great mystery here. The only potential problem arises on an instrument check ride when an IFR flight plan needs to be filed. The applicant can't legally do it until AFTER successful completion of the instrument check ride. Neither 61.51, 61.47, nor 61.3 (or any other reg) provides an exception.
Bottom line, 350 is in error, and you Cookmg are absolutely correct in questioning the upcoming situation. There is NO exception to the regulation requiring you to be instrument rated to file an instrument flight plan or to fly under IFR before you pass the practical.
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61.47 Status of an examiner who is authorized by the Administrator to conduct practical tests.
(a) An examiner represents the Administrator for the purpose of conducting practical tests for certificates and ratings issued under this part and to observe an applicant's ability to perform the areas of operation on the practical test.
(b) The examiner is not the pilot in command of the aircraft during the practical test unless the examiner agrees to act in that capacity for the flight or for a portion of the flight by prior arrangement with:
(1) The applicant; or
(2) A person who would otherwise act as pilot in command of the flight or for a portion of the flight.
(c) Notwithstanding the type of aircraft used during the practical test, the applicant and the examiner (and any other occupants authorized to be on board by the examiner) are not subject to the requirements or limitations for the carriage of passengers that are specified in this chapter.
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61.51 Pilot Logbooks
(e) Logging pilot-in-command flight time. (1) A recreational, private, or commercial pilot may log pilot-in- command time only for that flight time during which that person --
(i) Is the sole manipulator of the controls of an aircraft for which the pilot is rated;
(ii) Is the sole occupant of the aircraft; or
(iii) Except for a recreational pilot, is acting as pilot in command of an aircraft on which more than one pilot is required under the type certification of the aircraft or the regulations under which the flight is conducted.