The U.S. Federal Aviation Administration has ordered more than 1,000 Boeing 737 jets registered in the United States to be inspected for a potentially faulty part in the tail fin that could cause pilots to lose control of the plane if it fails.

The FAA reported:

We are adopting a new airworthiness directive (AD) for all The Boeing Company  Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. This AD was  prompted by reports of an incorrect procedure used to apply the wear and  corrosion protective surface coating to attach pins of the horizontal stabilizer rear spar. This AD requires  inspecting to determine the part number of the attach pins of the horizontal  stabilizer rear spar, and replacing certain attach pins with new, improved  attach pins. We are issuing this AD to prevent premature failure of the attach  pins, which could cause reduced structural integrity of the horizontal  stabilizer to fuselage attachment, resulting in loss of control of the airplane.

The concerns particularly regard new and very popular versions of the aircraft.

The inspections are not expected to affect airline schedules.
Airlines have to inspect and change their 737s as needed with the affected part by May 20.