It's always possible for a small airplane's engine to fail, the same way any other piece of equipment can fail. Federal Aviation Administration regulations are very strict to keep these risks as small as practical, but they can't eliminate the human factor. Was this accident caused by a problem with the airplane that was difficult to detect, or did the pilot simply allow this accident, and loss of a plane, to happen? Here's the relevant snippet from the preliminary National Transportation Safety Board (NTSB) report:
The pilot said that during climb-out, he was monitoring the airspeed so he could retract the flaps when the airplane reached 70 knots; however, at a height of 500 ft above the ground, he noticed that the airspeed was decreasing below 60 knots without out any changes to pitch attitude. The pilot thought the engine had lost power (he did not feel any vibration or unusual noise) and he pushed the nose over to gain airspeed. The pilot made a forced landing to a partially frozen creek, which resulted in substantial damage to the airframe.
Just so you all know, that explanation from the pilot makes very little sense. He should have lowered the nose (pitch down) after being above all obstacles, which at that airport is no greater than 200 feet up. After pitching down, his speed should have picked up from 63 knots to 79 knots pretty quickly. As that was happening, he should have verified his vertical speed was positive, then retracted the first notch of flaps. What the heck was he doing getting up near 500 ft before achieving the correct speed to climb out or retract the flaps. How do you "lose power" and somehow only notice it via your airspeed indicator in a Piper Warrior?
Unfortunately, it could be a year before the final report is released, and even then it might only take a cursory look at causes. Thankfully, nobody was seriously hurt, but I'm pretty annoyed regardless.