The phrase "a crucial question when" is correct and usable in written English.
It can be used to introduce an important inquiry that arises in a specific context or situation.
Example: "A crucial question when evaluating the effectiveness of the new policy is whether it meets the needs of the community."
Alternatives: "an important question when" or "a key question when".
This distracted us from a crucial question: when you see a specific case of inequality, how do you know it actually led to greater overall wealth?
When Yatom finds that cunning is no longer sufficient to assure survival, and that the various non-military alternatives have been exhausted, it is important to ask a crucial question: When will the West understand, as he does, that of all the options that were on the table, we are left with only the last one that has not been exercised yet to stop the Iranian nuclear program?
A crucial question when carrying out binding experiments for high-affinity interactions is whether the reaction has come to thermodynamic equilibrium.
Self-esteem is the crucial question when planning academics, social life, and after school activities.
And if indeed the oil futures markets was manipulated on that day it raises the very crucial question; when before and since have the oil futures trading markets been tampered with, how blatantly have the markets been distorted and how have these manipulations impacted the price of oil now and in the past.
This winter, Canarsie High School is still in the middle of an identity crisis, and now faces two crucial questions: When is a Chief not really a Chief?
As one of the large majority of Americans who oppose the continued American presence in Iraq, I hope the Senate Foreign Relations Committee will demand answers to some crucial questions when Gen. David H. Petraeus gives his report this week.
Perspective: Three Crucial Questions When Applying to M.D.-Ph.D. Programs by Skip Brass, 16 October 2009.
Herein lies a crucial question: what happens when our small islands of freedom become indistinguishable from the rest of the city?
But it is a crucial question to ask, especially when Europe has been facing so much outside pressure from the likes of the United States and the International Monetary Fund to focus on short-term Keynesian stimulus policies.
A crucial question is whether or when does treatment become necessary.
