Remember that the Strong's is referencing its opinion of the root word. The actual word is ויעף.
I dug out my Strong's book and it is H5774 in 1 SA 14:28 -- and in all the verses I've copied below.
The same word ויעף is used in the following verses. I'm copying from the KJV+ to show the Strong's in the verses. There does seem to be a discrepancy, although they have עף in common and are probably cognates.
Jdg 4:21 Then JaelH3278 Heber'sH2268 wifeH802 tookH3947 (H853) a nailH3489 of the tent,H168 and tookH7760 (H853) an hammerH4718 in her hand,H3027 and wentH935 softlyH3814 untoH413 him, and smoteH8628 (H853) the nailH3489 into his temples,H7541 and fastenedH6795 it into the ground:H776 for heH1931 was fast asleepH7290 and weary.H5774 So he died.H4191
1Sa 14:28 Then answeredH6030 oneH376 of the people,H4480 H5971 and said,H559 Thy fatherH1 straitly charged the people with an oath,H7650 H7650 (H853) H5971 saying,H559 CursedH779 be the manH376 thatH834 eatethH398 any foodH3899 this day.H3117 And the peopleH5971 were faint.H5888
1Sa 14:31 And they smoteH5221 the PhilistinesH6430 thatH1931 dayH3117 from MichmashH4480 H4363 to Aijalon:H357 and the peopleH5971 were veryH3966 faint.H5888
2Sa 21:15 Moreover the PhilistinesH6430 hadH1961 yet warH4421 again withH854 Israel;H3478 and DavidH1732 went down,H3381 and his servantsH5650 withH5973 him, and fought againstH3898 (H853) the Philistines:H6430 and DavidH1732 waxed faint.H5774
2Sa 22:11 And he rodeH7392 uponH5921 a cherub,H3742 and did fly:H5774 and he was seenH7200 uponH5921 the wingsH3671 of the wind.H7307
Psa 18:10 And he rodeH7392 uponH5921 a cherub,H3742 and did fly:H5774 yea, he did flyH1675 uponH5921 the wingsH3671 of the wind.H7307
Isa 6:6 Then flewH5774 oneH259 ofH4480 the seraphimsH8314 untoH413 me, having a live coalH7531 in his hand,H3027 which he had takenH3947 with the tongsH4457 from offH4480 H5921 the altar:H4196
Hebrew (HOT+)
Jdg_4:21 ותקח יעל אשׁת־חבר את־יתד האהל ותשׂם את־המקבת בידה ותבוא אליו בלאט ותתקע את־היתד ברקתו ותצנח בארץ והוא־נרדם ויעף וימת׃
1Sa_14:28 ויען אישׁ מהעם ויאמר השׁבע השׁביע אביך את־העם לאמר ארור האישׁ אשׁר־יאכל לחם היום ויעף העם׃
1Sa_14:31 ויכו ביום ההוא בפלשׁתים ממכמשׂ אילנה ויעף העם מאד׃
2Sa_21:15 ותהי־עוד מלחמה לפלשׁתים את־ישׂראל וירד דוד ועבדיו עמו וילחמו את־פלשׁתים ויעף דוד׃
2Sa_22:11 וירכב על־כרוב ויעף וירא על־כנפי־רוח׃
Psa_18:10 (18:11) וירכב על־כרוב ויעף וידא על־כנפי־רוח׃
Isa_6:6 ויעף אלי אחד מן־השׂרפים ובידו רצפה במלקחים לקח מעל המזבח׃