Each of these is a refusal this regime lets a counterparty attempt, paired with the answer to it. Reading them before you write is worth more than any amount of polish on the letter itself.
"It was a technical problem, so we are exempt"
high likelihoodThe carrier invokes the Art. 120 exemption for remedying a defect threatening the life or health of passengers.
What answers it
That limb is real and wider than its European equivalent, but it is not a blanket excuse for any maintenance issue. The defect must have threatened life or health, and the carrier has to prove it. Ask what the defect was, what the technical log records, and why it was not found at the previous check. A routine unserviceability discovered at the gate is not the same as a safety-critical failure.
Воздушный кодекс Российской Федерации, ст. 120 (Ответственность перевозчика за просрочку доставки пассажира, багажа или груза) — ст. 120
"Here are your 250 roubles, that closes the matter"
high likelihoodThe carrier pays the Art. 120 fine and treats it as the full extent of its liability.
What answers it
The fine and the damages are separate limbs of the same article, and the second paragraph says so. The fine is a penalty for lateness; the damages are compensation for loss. Accepting the fine does not compromise the damages claim, and neither touches the consumer statute's moral-harm head or the 50% penalty for refusing a justified claim.
Воздушный кодекс Российской Федерации, ст. 120 (Ответственность перевозчика за просрочку доставки пассажира, багажа или груза) — ст. 120
"The delay was weather, so nothing is provided"
high likelihoodThe carrier refuses meals, calls and a hotel on the footing that the delay was not its fault.
What answers it
Para. 99 of the Federal Aviation Rules imposes the care obligations regardless of the cause of the delay. Weather exempts the carrier from the Art. 120 fine; it does not exempt it from feeding you after four hours or accommodating you after eight. These are different provisions in different instruments.
Федеральные авиационные правила, приказ Минтранса России от 28.06.2007 № 82, п. 99 — п. 99