Regulators are ready to allow Boeing's (BA 0.25%) troubled 737 MAX 9 aircraft to fly again, but the decision came at a steep cost to the aerospace giant's growth plans. Shares of Boeing traded down about 5% as of 10:30 ET Thursday as investors try to figure out where Boeing goes from here.

Forget about business as usual at Boeing

Boeing has been a tough stock for investors to love in recent years. The company's problems began in late 2018 with a pair of fatal 737 MAX crashes that led to an 18-month safety-related grounding of the jet. The MAX is flying again but continues to be plagued by problems.

Earlier this month, about 200 737 MAX 9 planes were grounded after a door plug separated midflight, causing a plane to depressurize.

Late Wednesday, the Federal Aviation Administration (FAA) approved an inspection and maintenance process that, upon successful completion, would allow individual airframes to return to service. However, the FAA also barred Boeing from increasing its production rate until the regulator is reassured that the planes' problems are under control.

"Let me be clear: This won't be back to business as usual for Boeing," FAA Administrator Mike Whitaker said in a statement. "We will not agree to any request from Boeing for an expansion in production or approve additional production lines for the 737 MAX until we are satisfied that the quality control issues uncovered during this process are resolved."

The FAA provided no estimate on how long the limitation would remain in place, and it did not specify the number of planes Boeing could build. But the decision is bad news for Boeing and its suppliers, as investors had expected an increase in deliveries in 2024.

Shares of Boeing are now down 22% for the year.

Is Boeing a buy after its recent stock plunge?

Boeing shares are more than 50% below where they traded prior to the first 737 MAX crash. The bull case from here is relatively straightforward. Boeing is one half of a global aircraft manufacturing duopoly at a time when airlines are lining up to buy new jets. It seems that if Boeing can only get its act together, the stock should be poised for a rapid ascent.

Alas, the recent history of Boeing provides no reason for confidence that the company can normalize manufacturing anytime soon. With the FAA breathing down its neck for the foreseeable future, Boeing will need to be conservative in its growth plans, which will limit the upside.

Boeing also has billions in debt that it added during the crisis and pandemic and had hoped to pay down through higher deliveries.

The stock at its current valuation is tempting, but the recent track record is clear. Investors should wait for proof that the crisis is behind Boeing before buying in.