The authorities are probing the latest incident in a spate of Housing Board lift glitches, which has left residents concerned.
The use of one of two lifts at Block 317, Ang Mo Kio Street 31 was suspended on Tuesday by the Building and Construction Authority (BCA) after it malfunctioned on Monday evening. Ms Evi Lisnawati fell and hit her back after Lift A, which she was taking to the ground floor, suddenly shot up 17 storeys.
It then stalled between the 19th and 20th storeys, trapping the 36-year-old Indonesian maid for over an hour before she was rescued. BCA said Ang Mo Kio Town Council (AMKTC), which manages the lift, is now required to appoint an independent authorised examiner to inspect it.
The authorised examiner must also recommend rectification works and submit its findings to BCA.
A BCA spokesman said: "BCA will allow the lift to resume operations only when the investigation and rectification works are completed, and BCA is satisfied that the lift is safe for use."
A spokesman for AMKTC said this is the first time the 23-year-old lift has caused problems.
In the light of Monday's incident, he said the town council is stepping up its lift maintenance, which is usually carried out once a month, although it did not specify how.
The lift, which was manufactured by Fujitec, was last serviced on Feb 23. The AMKTC spokesman added: "The investigation is still ongoing and we shall await the conclusion from the investigators and (professionals) before proceeding further."
Fujitec Singapore's chief operating officer William Wong said his company's technicians are assisting BCA with investigations.
Asked what might have caused the accident, Mr Wong said: "Until we are able to pinpoint the cause, I don't want to speculate."
Some residents had noticed problems with the two lifts in the block even before the accident.
Administrator Lim Geok Hong, 53, who has lived there for over 20 years, said both lifts would occasionally fail to move even after the doors shut.
She said in Mandarin: "You have to push the lift doors slightly before the lift will start to move."
Retiree Wong Leat, 68, said that in the two weeks before the accident, he had sometimes felt Lift A shaking while it was moving.
"Even my granddaughters were scared," he said.
AMKTC chairman Ang Hin Kee said that the block's Lift B is "functioning normally" and checks have been carried out by BCA and Fujitec.
He added: "We will continue to check it daily over the next few days. We are also talking with residents to allay their concerns."
Last October, an 85-year-old Jurong resident's hand was severed after the doors of the lift she was in closed on her dog leash. She also fell and broke her leg.
In January, a faulty HDB lift in Punggol's Edgefield Plains was suspended from use after one of the lift's inner doors stayed open while the lift moved.
Correction note: An earlier version of the article stated that the town council must recommend rectification works and submit its findings to BCA. This is incorrect, the recommendation should be from the authorised examiner.