After reading this discussion, I'd like to know what example sentences distinguish the meaning of the words lept, leapt, and leaped from each other?
The past tense of leap is rightly spelled leapt when pronounced
As you see, the sound change is more consistent than the spelling, but leapt is not wholly without precedent in other forms even when spelled that way.
Almost ten years ago, I checked and recorded the relative popularity of leaped and leapt in Google results, because the following assertion in Webster's Dictionary of English Usage (1989) intrigued me: "In American English, leaped and leapt seem to be used with about equal frequency." Recognizing that leapt is somewhat more common in British (and British Commonwealth) English than in U.S. English, I decided to run Google searches for the two terms, reasoning that if leaped came out significantly ahead in undifferentiated results, it was probably considerably more popular than leapt in U.S. usage.
My first round of searches for leaped and leapt (undated, but probably in 2004 or 2005) generated 6.2 million matches for leaped and 4.7 million matches for leapt. A second run, on 11 August 2010, produced these unexpected numbers: 8.73 million for leaped, 8.53 million for leapt, and 401,000 for lept. Today (22 January 2013), I ran the searches again and got these numbers: 7.06 million for leaped, 10.5 million for leapt, and 1.11 million for lept.
With regard to absolute numbers, Google searches are utterly unreliable because they generate so many repetitious matches for the same content. But for indicating shifts in relative popularity, I think that they can be useful. And in this case, a rather impressive shift in such popularity is evident—away from leaped and toward leapt. The numbers also suggest that lept is very far from vanishing as a variant spelling, though Merriam-Webster Online as yet declines to accept it as one.
An Ngram Viewer search for leaped, leapt, and lept confirms my initial impression/assumption that leaped is more common in published print content than leapt—and indeed indicates that it has been consistently so for more than 200 years. However, the rise of leapt in Google results and the absence of copyediting in much published work these days suggest that leapt may soon vindicate Webster's Dictionary of English Usage's prematurely enthusiastic assessment of its popularity in the United States.
I found this quote here by Pam Peters (The Cambridge Guide to English Usage), and she says:
Based on this, I think that you can use 'leaped' or 'leapt'; both are acceptable past-tense and past-participle forms for the verb leap. As Bryan A. Garner says³: “Because leapt is pronounced /lept/, the mistaken form lept is frequently encountered.”
¹CCAE: The Cambridge International Corpus of American English
²BNC: British National Corpus
³A Dictionary of Modern American Usage