In June 1941, Kapitan Ilyin served in the 13 IAP-KBF.

On 22 June 1941, he claimed a Junkers over the Baltic.
This victory wasn’t confirmed because ground observers didn’t saw the crash since it was over water.

Together with Leytenant Zaytsev he met four Bf 109s over the Bay of Riga on 25 October 1941.
Zaytsev’s I-153 was hit in the beginning of the combat but he managed to escape with his damaged aircraft. This left Ilyin (I-153 ‘24’) alone but despite this, he managed to hit a Bf 109 from a distance of 400 meters. The German fighter, which probably was from JG54, crashed into the sea near Saaremaa Island.
Ilyin was also credited with a damaged Bf 109.

On 18 January 1942, the 13 IAP-KBF became the 4 GIAP-KBF.

On 30 September, the I-16s of the 4 GIAP-KBF clashed with Bf 109s, losing four aircraft and getting eight damaged, three of the seriously. Of the 19 I-16s at hand by the regiment that morning, only seven remained operational a few hours later. 4 GIAP’s casualties this day included three veterans: the deputy CO Mayor IIyin; the Komissar in 2 AE, Starshiy Politruk Grigoriy Semyonov; and Starshiy Leytenant Vladimir Petrov (3 and 6 shared victories) where only Ilyin survived with injuries.
It seems that they had been in combat with JG 54, which claimed seven I-16s in two engagements during the day.
In the first engagement between 10:20 and 10:30, four were claimed by Unteroffizier Rudolf Fischer-Bötow of Stab III/JG 54 (at 10:20), Oberleutnant Heinz Lange of 1./JG 54 (at 10:27) and Unteroffizier Siegfried Müller of 9./JG 54 (two aircraft at 10:29 and 10:30).
During the second engagement between13:45 and 13:58, three more were claimed by Feldwebel Josef Brechtl of 7./JG 54 (at 13:45) and Unteroffizier Siegfried Müller of 9./JG 54 (two aircraft at 13:55 and 13:58).
21 IAP-KBF and 71 IAP-KBF also lost one I-16 each during the day.

Ilyin ended the war with 2 biplane victories.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1941
1	22/06/41		1	Junkers (a)	Destroyed	I-153		Baltic	13 IAP-KBF
2	25/10/41		1	Bf 109 (b)	Destroyed	I-153	’24’	Saaremaa Island	13 IAP-KBF
	25/10/41		1	Bf 109 (b)	Damaged	I-153	’24’	Saaremaa Island	13 IAP-KBF

Biplane victories: 2 destroyed, 1 damaged.
TOTAL: 2 destroyed, 1 damaged.
(a) This victory wasn’t confirmed because ground observers didn’t saw the crash since it was over water.
(b) Claimed in combat with Bf 109s probably from JG54.

Sources:
Black Cross/Red Star Volume III - Christer Bergström, Andrey Dikov and Vlad Antipov, 2006 Eagle Editions Ltd., ISBN 0-9761034-4-3
Luftwaffe Claims Lists - Tony Wood
Triumf a tragedie - Milos Sedivy and Valerii Dymich, 2001 Svet kridel, ISBN-80-85280-70-1 kindly provided by Tomáš Polák
Additional information kindly provided by Ondrej Repka.