This quiz is formulated about a test for the CFI-Airplane rating that happened in America nearly 50 years ago, so you might take that into account in formulating your answer.
Our CFI candidate held a current Flight Physical appropriate to his ratings, a current Private Pilot Certificate, an FCC Radiotelphone Operator's Permit, a current Commercial Pilot endorsement and a current Instrument endorsement for the test aircraft used, a Piper PA-28 Cherokee with all endorsements signed off and in order in his logbooks. He had an accident-free record and all requisite number of hours for the CFI-Airplane rating he sought. He had completed all ground school training for the CFI-Airplane rating successfully from an authorized ground school instructor and was endorsed for that. He also had received and was endorsed in his logbook for all areas of operation in flight proficiency training in flight for an airplane, single engine land from a rated CFI-Airplane single engine-land instructor.
On his CFI examination day he flew from his airport a short distance to the local General Aviation District Office in the PA-28 which had a current Annual Airworthiness Inspection signed in the aircraft's logbook which was in the test airplane. At his appointment time he met with the FAA Flight Examiner, introduced himself and exchanged pleasantries, where his complete logs and the aircraft's logs were reviewed by the FAA Flight Examiner, finding all in order. They then walked out to the test aircraft and did a complete expanded aircraft pre-flight test guided by the aircraft's pre-flight checklist book with no aircraft discrepancies found.
Upon their boarding of the PA-28 for the in-flight exam for the CFI-Airplane rating, the FAA Flight Examiner announced the CFI candidate FAILED the CFI-Airplane flight exam.
Question-What did the CFI candidate do or nor do that caused him to fail before they even took off for the flight test portion of the CFI-Airplane examination? Be specific in your answer.