Short answer. Yes, if he knew of the flaw and did not tell you. Someone who lends a thing and stays silent about a defect he is aware of must answer for the damage you suffer because of it. The claim turns on his knowledge, not on the thing simply turning out to be faulty.
What the law says
The bailor who, knowing the flaws of the thing loaned, does not advise the bailee of the same, shall be liable to the latter for the damages which he may suffer by reason thereof.
Civil Code, Article 1951 — The Lender's Liability for Known Flaws. Read the full provision →
Lender and borrower, in the Code's words
In a free loan of a thing, the Civil Code calls the lender the bailor and the borrower the bailee. Article 1951 provides that The bailor who, knowing the flaws of the thing loaned, does not advise the bailee of the same, shall be liable to the latter for the damages which he may suffer by reason thereof. The lender is not made to guarantee that everything he lends is sound. What he must not do is keep quiet about a defect he already knows about. Lending is usually a favour, and the law asks only that the favour be an honest one.
Knowledge is the hinge
Three things must be shown: that the thing had a flaw, that the lender knew of it, and that he did not warn you. A lender who was genuinely unaware — a fault buried inside a machine that had never given him trouble — falls outside this article. A lender who says nothing about brakes he knows are failing, a ladder he knows is cracked, or a generator he knows overheats sits squarely inside it. Knowledge is usually proved by circumstance: earlier repairs, complaints from other users, messages, or the plain fact that the defect was obvious to anyone who handled the thing.
The damage must come from that flaw
The lender answers for the damages which he may suffer by reason thereof — the harm traceable to the undisclosed defect. Medical expenses, income lost while you could not work, and property destroyed in the incident are the usual heads, and each has to be proved rather than estimated. Harm arising from something else, or from the borrower's own misuse, is not recoverable here. Where a manufacturer or a repairer also bears responsibility, that is a separate avenue; a borrower is not confined to claiming from the lender merely because the lender is the person he happens to know.
What it does not do, and what to keep
The article does not turn every lender into an insurer, and it gives no compensation simply because a borrowed thing broke down. It also says nothing about who bears the cost of ordinary repairs during the loan, which the rules on free loans deal with elsewhere. If you have been injured, keep the thing itself where you safely can, photograph the defect, obtain a medical record on the day rather than weeks later, and preserve any message in which the lender mentioned the problem. Take advice promptly, because claims for injury and damage are subject to time limits.