Mary Ann,  I was a crew chief with HMM-262 but later than 67 but I will pass this request on and maybe some guys from that time period will be able to comment.

I was in HMM-165 in late 1967 but the only Navy personnel I remember flying with us were Hospital Corpsmen to patch up wounded Marines. We were on the USS Valley Forge LPH-8 during TET in very early 1968 and later on the USS Tripoli LPH-10 and supported Battalions of Marines in combat as needed. We transported them in and out of the combat zones but never flew with Navy personnel that I can recall. No sure this would help.....

@Dale-A-Riley Thank you very much.  I may never find the exact answer, but I have gotten this far.  I just keep trying whatever comes to mind.  I'm sure this was for a very short time and was not common practice at all.  I also have no idea why he underlined HMM-262.  The Texas Tech Vietnam Archives have After Action Reports for a lot of HMM squadrons, but not those for HMM-262 for that time period.  I will check with the Marine Corps History people.  It is circumstantial evidence that he was on a Marine Corps helicopter, but the Navy HC-1 men say not.  Hard to say. 

@JoeReed  I have been wondering about the LPH's, so that is useful information.  This would have been shortly after the first hill fights of Khe Sanh.  I've read the Marine Corps was stretched quite thin at that time.  It would have been for a very short time and quite unusual.  My husband isn't even listed as not present in the muster logs, but when I found his best friend, he told me he definitely left on a helicopter.  Which service, which helicopter?  I may never find out, but I keep asking.  I've surprisingly found a lot of men who were shipmates who remember him.  Maybe sometime I will find someone who knows  the whole story.  Thank you for taking the time to respond!

rhodema,  do you have his “service record” ?   You need to request one from the National Personnel Records Center, 1 Archives Drive. St. Louis, MO 63138.  It can be done on-line if you google for Navy records.  It will have everything-and I mean everything from the day he signed up till the day he signed out.  I have a “Record of Service” form “NAVMC 118” that list every duty station and outfit I was assigned to - day I got there - primary duty - proficiency marks and day I left.  Then next outfit, then next and so on for my four years.

‘It will have a copy of DD-214, schools and training, combat history-expeditions-awards record page.  If he flew as crew then there will be a page showing outfit, month by month flight hours.

‘That is where you need to start.  Good Luck

@Dale-A-Riley Thanks for the tip.  I did get his records & have his DD-214, except the medical records which are "lost." Unfortunate, because he did get shot through his leg when on the helicopter.  None of this is in his record.  When some told me he was making this up, I started digging.  He was not the type to make stuff up, rarely talked about his service.  I went through all the deck logs for both his ships, ordered and reviewed the personnel records from NARA for both ships.  Nothing.  I did find 7 sailors/friends who verified much of what he said.  It did happen.  It was a very busy, hard time.  If he was "loaned" to the Marine Corps for a short time due to some sudden crisis, I can see why the paperwork doesn't exist.  Everyone was trying to fight a war.  Thanks again for reaching out.  Mary Ann, former Lt. Army Nurse Corps Reserves